— Thirteen is the 6th smallest prime number; the next is seventeen. 13 is the second Wilson prime. 13 is the fifth Mersenne prime exponent, yielding 8191. 13 is also the third lucky prime.
— 13 is the second star number and the seventh Fibonacci number. As it is an odd-indexed Fibonacci number, it is a Markov number, appearing in solutions to the Markov Diophantine equation: (1, 5, 13), (1, 13, 34), (5, 13, 194), …
— There are 13 Archimedean solids.
— 13 goes into 999,999 exactly 76,923 times, so vulgar fractions with 13 in the denominator have six digit repeating sequences in their decimal expansions.
— At 13, the Mertens function sets a new low of -3, subseded later at 31 with a value of -4.
— 13 is the only positive integer that is the fourth root of the sum of the squares of two successive positive integers (119 and 120).
— The 13th root is the most famous integer root calculation record, because 13 is the first prime number over 10 such as the last digit of a 13th integer power is the same as the last digit of its 13th root.
— In base 10, the smallest prime with a composite sum of digits is 13.
— 13 is a repdigit in base 3 (111).
— The atomic number of aluminium
— The number of dimensions in some theories of relativity
— Messier object M13, a magnitude 7.0 globular cluster in the constellation Hercules, also known as the Hercules cluster. It is one of the brightest and best-known of the globular clusters.
— The New General Catalogue object NGC 13, a spiral galaxy in the constellation Andromeda
— The Saros number of the solar eclipse series which began on -2561 September 12 and ended on -1046 March 9. The duration of Saros series 13 was 1514.5 years, and it contained 85 solar eclipses.
— The Saros number of the lunar eclipse series which began on -2313 May 20 and ended on -1015 July 6. The duration of Saros series 13 was 1298.1 years, and it contained 73 lunar eclipses.
— The 13th moon of Jupiter is Elara.
— The known universe is currently thought to be about 13.7 billion years old, with an error of about one percent.
— There are 13 zodiac constellations, which consist of the 12 signs in the astrological zodiac and Ophiuchus.
— The number of participants at the Last Supper
— Counting both Judas and Matthias, there were thirteen apostles
— Thirteen was once associated with the Epiphany by Christians, the child Jesus having received the Magi on his thirteenth day of life.
— In Judaism, 13 signifies the age of maturity (bar mitzvah) for boys
— The number of principles of Jewish faith according to Maimonides
— According to the Torah, God has 13 Attributes of Mercy
— In modern day Wicca, thirteen is considered the maximum size of a coven, and in some traditions is the ideal number of members. There are also 13 goals of a witch
— The number of circles, or “nodes”, that make up Metatron’s Cube.
— The number of gods (there were 12) at a banquet that was crashed by the evil spirit Loki (making 13) who killed one of the guests with a poison arrow.
— 13 is a 1998 album by German band Die Ärzte.
— 13 is a 2005 album by American band Six Feet Under.
— 13 is a 2003 album from Heavy Metal band Solace.
— 13 is a 1999 album by British band Blur.
— 13th Floor Elevators, a Texan psychedelic band.
— 13 Engines, a Canadian alternative rock band.
— John Mayer’s album Room for Squares does not contain a track 13. Instead track 13 is one second of silence before skipping directly to track 14.
— “Thirteen Ways of Looking at a Blackbird,” poem by Wallace Stevens.
— In movie titles:
— — Thirteen (2003)
— — Thirteen Days (2000)
— — The Thirteenth Floor (1999)
— — 13 Going on 30
— — Apollo 13
— — Thir13en Ghosts (2001)
— — 13 Conversations About One Thing
— — Assault on Precinct 13 (1976)
— — Assault on Precinct 13 (2005)
— — Dementia 13
— — Ward 13 (animated short)
— — Friday the 13th series (1980-2003)
— — Nightmare on the 13th Floor (1990)
— Golgo 13, an anime about a powerful hitman. The name comes from Golgotha, the site of Jesus’s crucifixion.
— Strauss and Howe named Generation X the “Thirteenth Generation”.
— In the episode of King of the Hill when Connie has her first period and she goes with Hank to the Megalomart to buy tampons, the feminine hygiene items are in Aisle 13. This was changed to Aisle 8A when the episode reran.
— A song by the band Osker, also the title of a song by the band Bigwig
— Every book in A Series of Unfortunate Events has 13 chapters, and it has been reported that there will be 13 books in the series when it is finished.
— The 13 Ghosts of Scooby Doo, an animated TV series where the venerable cartoon dog finds and opens a chest containing 13 of the most powerful ghouls in the world, and is charged with putting them back.
— XIII, a French comic book about an assassin.
— — XIII, a video game based on the aforementioned comic book.
— Organization XIII, an organization of 13 non-existent beings dubbed “Nobodies” who star in the game Kingdom Hearts 2.
— The number of Stepchildren in the Noon Universe created by Arkady and Boris Strugatsky
— The number of apostles who divided Earth into Stark and Arcadia in the alternate universe of The Longest Journey as well as the time, in millennia, that the Balance between the twin worlds was projected to last.
UNITED STATES OF AMERICA
— The number of original colonies the United States was founded from. The original flag had thirteen stars, one for each state. New stars have since been added whenever a new state joins the union, but the idea of adding stripes for new states was soon dropped, so the American flag to this day has thirteen horizontal stripes: six white ones and seven red ones.
— The Great Seal of the United States has:
— — 13 levels of the truncated pyramid,
— — 13 letters in “E Pluribus Unum”, which appears in the banner running through the eagle’s beak on the right side of the bill’s reverse.
— — 13 letters in the phrase “Annuit Coeptis”, which appears over the pyramid on the left side of the bill’s reverse.
— — 13 stars above the Eagle,
— — 13 leaves on the olive branch,
— — 13 olives on the olive branch,
— — 13 arrows held by the Eagle, and
— — 13 bars on the shield.
— The number of guns in a gun salute to U.S. Army, Air Force and Marine Corps Major Generals, and Navy and Coast Guard Rear Admirals Upper Half.
— The Naval Jack of the United States has 13 stripes, 7 red and 6 white, the rattlesnake has 13 buttons on its rattle, and the motto “Don’t Tread on Me” has 13 letters
IN OTHER FIELDS
— The original number of members of The Thirteen Club.
— The number of loaves in a “baker’s dozen”
— The expression, “A year and a day” refers to 13 28-day lunar months plus 1 day
— The number of Popes named Innocent, for which an honor society containing 13 members at the University of Nebraska is named (“The Society of Innocents”)
— The number of cards in a single suit of a standard deck of playing cards
— The ASCII and Unicode value for carriage return
— “Unlucky for some”, according to bingo callers
— The number of players in a rugby league team
— The number of Plutonium slugs in Fat Man, the atomic bomb dropped on Nagasaki
— The number on a Hell’s Angel’s patch or tattoo that refers to the thirteenth letter of the alphabet, M, for “marijuana”
— 13, or “X3”, is the number of the Mexican street gang Sureños. It refers to the thirteenth letter of the alphabet, M, for Mexico
— In rugby union one of the centres, most often but not always the outside centre, wears the 13 shirt
— Israel Naval covert unit – Shayetet 13
— Former professional wrestler Tazz used the number 13 in his ring gear, merchandise, and Titantron video, signifying the 13 years he wrestled in the independent circuit and ECW before being signed by WWE
— A card game very similar to Tien len.
— The ancient card game ‘Boumpha’ has 13 different cards
— In tarot, card no. 13 is “the Death”