13

This number is a prime.

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Photo credit: Patrick Kik

The number of 13-digit primes is an emirp. Recall the smallest emirp. [Green]

The lesser member of the smallest twirp, i.e., a emirp pair such that each member also belongs to a twin prime pair. In this case, the associated primes are 11 and 29. [Green]

The smallest prime such that if its digits are rendered in a prime base p, the result, 13 (base p), is never prime. [Green]

There are 13 cards of each suit in a deck of playing cards. [Green]

'Friday the 13th' is a franchise that consists of several movies, a television show, novels, comic books, and related merchandise. Submitted on Friday the 13th. [Green]