**>>> This site will be down for maintenance (and submissions blocked) intermittently Wed 21 Jan 2021.**

# 512

This number is a composite.

512 is the smallest (and only known) cube such that 512*2^512-1 is prime. [Gupta]

512 = 2^9. Both 2^9 +/- 9^2 are prime. This is the smallest number of the form 2^n such that both 2^n +/- n^2 are prime. [Astle]

(There is one curio for this number that has not yet been approved by an editor.)

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