Here is one special case as a category:
Quote:
A circular prime number is a number that remains prime on any cyclic rotation of its digits (in base 10).

https://en.wikipedia.org/wiki/List_o...ircular_primes
Another:
Quote:
Primes that become a different prime when their decimal digits are reversed. The name "emirp" is obtained by reversing the word "prime".

https://en.wikipedia.org/wiki/List_o...numbers#Emirps
Last fiddled with by a1call on 20160316 at 00:11
