6689

This number is a prime.

+ The smallest invertible prime whose digits are circular and composite. [Punches]

+ The NSW number with index 6689 is prime. These numbers arise when addressing the following question: "Is there a finite simple group whose order is a square?"

+ The first occurrence of a twin prime pair (6689, 6691) that both are invertible primes. [Beedassy]

+ The smallest invertible Yarborough prime. [Jha]

Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell