In Mathematics
The number 13 is the sixth prime number, and the smallest emirp (prime which is a different prime when reversed). It is also a Fibonacci number, a happy number, and one of only 3 known Wilson primes.
Since 52 + 122 = 132, (5, 12, 13) forms a Pythagorean triple.
There are 13 Archimedean solids, and a standard torus can be sliced into 13 pieces with just 3 plane cuts.
Read more about this topic: 13 (number)