255

This number is a composite.

+ 255 is the least odd integer greater than 3 which is not the sum of two distinct powers of two and a prime.

+ 255 (3*5*17) is a sphenic number, i.e., the product of three distinct primes. The next sphenic number is 258 (2*3*43). Curiously, 32 + 53 + 1743 is prime. [Honaker]

+ The smallest number n such that 2^99+n is prime. [Loungrides]

Printed from the PrimePages <primes.utm.edu> © G. L. Honaker and Chris K. Caldwell