Thirteen

Thirteen is the 6th smallest prime number, the next is seventeen.

13 goes into 999,999 exactly 76,923 times, so fractions with 13 in the denominator have six digit repeating sequences in their decimal expansions.

Thirteen is also:

• Regarded as an unlucky number in many cultures. Unreasoned fear of the number 13 is termed triskaidekaphobia.
• In the Christian religion, the number is considered significant since there were thirteen present at the Last Supper. Also, if both Judas and Matthias are counted, there were thirteen apostles.
• There are thirteen loaves in a baker's dozen.
• In bingo it is called Unlucky for some.