13 (number)

13 (thirteen) is the natural number following 12 and preceding 14.
Folklore surrounding the number 13 appears in many cultures around the world: one theory is that this is due to the cultures employing lunar-solar calendars (there are approximately 12.41 lunations per solar year, and hence 12 "true months" plus a smaller, and often portentous, thirteenth month). This can be witnessed, for example, in the "Twelve Days of Christmas" of Western European tradition.
The number 13 is a prime number, happy number and a lucky number. It is a twin prime with 11, as well as a cousin prime with 17. It is the second of only 3 Wilson primes: 5, 13, and 563. A 13-sided regular polygon is called a tridecagon.
In Germany, according to an old tradition, 13 (dreizehn), as the first compound number, was the first number written in digits; the numbers 0 (null) through 12 (zwölf) were spelled out. The Duden (the German standard dictionary) now calls this tradition (which was actually never written down as an official rule) outdated and no longer valid, but many writers still follow it.
Thirteen is one of two numbers within the teen numerical range (13–19), along with fifteen, not derived by cardinal numeral (three) and the teen suffix; instead, it is derived from the ordinal numeral (third).
In Shia, 13 signifies the 13th day of the month of Rajab (the Lunar calendar), which is the birth of Imam Ali.
In Catholic devotional practice, the number thirteen is also associated with Saint Anthony of Padua, since his feast day falls on June 13. A traditional devotion called the Thirteen Tuesdays of St. Anthony involves praying to the saint every Tuesday over a period of thirteen weeks. Another devotion, St. Anthony's Chaplet, consists of thirteen decades of three beads each.
According to famous Sakhi (evidence) or the story of Guru Nanak Dev Ji, when he was an accountant at a town of Sultanpur Lodhi, he was distributing groceries to people. When he gave groceries to the 13th person, he stopped because in Gurmukhi and Hindi the word 13 is called terah, which means yours. And Guru Nanak Dev Ji kept saying, "Yours, yours, yours..." remembering God. People reported to the emperor that Guru Nanak Dev Ji was giving out free food to the people. When treasures were checked, there was more money than before.
A common tradition in the religion Wicca holds that the number of members for a coven is ideally thirteen, though this tradition is not universal.
The number 13 is considered an unlucky number in some countries. The end of the Mayan calendar's 13th Baktun was superstitiously feared as a harbinger of the apocalyptic 2012 phenomenon. Fear of the number 13 has a specifically recognized phobia, triskaidekaphobia, a word first recorded in 1911. The superstitious sufferers of triskaidekaphobia try to avoid bad luck by keeping away from anything numbered or labelled thirteen. As a result, companies and manufacturers use another way of numbering or labelling to avoid the number, with hotels and tall buildings being conspicuous examples (thirteenth floor). It is also considered unlucky to have thirteen guests at a table. Friday the 13th has been considered an unlucky day.
There are a number of theories as to why the number thirteen became associated with bad luck, but none of them have been accepted as likely.
A baker's dozen, devil's dozen, long dozen, or long measure is 13, one more than a standard dozen. The thirteenth loaf is called the vantage loaf because it is considered advantageous overall to get 13 loaves for the price of 12.
In a tarot card deck, XIII is the card of Death, usually picturing the Pale Horse with its rider.