Number 57 is Prime

So says the world's most famous mathematician, in a new paper. See page 27 where the authors apply their theory to example primes, 53 and 57. 53 is prime, but 57 is 19*3.

Apparently it is an inside joke among mathematicians to say 57 is prime, as if they cannot be bothered to check. See the Wikipedia article, where 57 is called the Grothendieck prime, as a math joke about the most famous abstract-thinking mathematician.