1. Thirteen is a prime number, only divisible by itself and 1.
2. Triskaidekaphobia is the fear of the number 13.
3. Thirteen may be considered a “bad” number simply because when a group of 13 objects or people is divided into two, three, four or six equal groups, there is always one leftover, or “unlucky”, object or person.
4. Italians omit the number 13 from their national lottery.
5. Many airports skip the 13th gate. Airplanes have no 13th row.
6. More than 80 percent of high-rises lack a 13th floor.
7. At the Universal Studios sound stages in California, there is no sound stage numbered 13.
8. The number of steps, according to Egyptian lore, between life and death is 13.
9. A rondeau is a poem with 13 lines; the opening phrase is repeated as the refrain of the second and third stanzas.
10. 13 is a baker’s, devil’s or long dozen.
11. The arrest and murder of the Knights Templar occurred on Friday October 13, 1307. This event is sometimes said to be the origin of the supposed unluckiness of Friday the 13th.
12. The number of cards in a single suit of a standard deck of playing cards.
13. It is considered unlucky to have thirteen at a table or in a company. The number 13, in the Christian faith, is the number of people at the Last Supper, with the 13th guest at the table being the traitor, Judas.