13

This number is a prime.

Just showing those entries submitted by 'Silva': (Click here to show all)

 Photo credit: Patrick Kik
The first Fibonacci emirp. [Silva]

There are 13 composite numbers between 13 and its reversal. [Silva]

The longest name of a book of the KJV Bible is Thessalonians with 13 letters. [Silva]

The smallest prime formed from consecutive odd digits. [Silva]

13!+31!-1 is prime. [Silva]

The smallest prime sum of semiprimes. [Silva]

The only Fibonacci prime equal to the sum of the squares of two consecutive Fibonacci primes. [Silva]

13 squared equals the sum of the first five emirps. [Silva]

The number of five-digit primes formed from the five nonzero nonprime digits. [Silva]

13 + (1+3) is the next emirp. The only two-digit emirp with that property. [Silva]

The smallest expansive prime, i.e., a prime from which another can be obtained by repeating its digits in order, each digit repeated d times. [Silva]

The first member of the smallest pair of cousin emirps. [Silva]

(There are 4 curios for this number that have not yet been approved by an editor.)