21

This number is a composite.

Single Curio View:   (Seek other curios for this number)
Is 21 the largest Fibonacci number that falls between cousin primes (19 and 23)? [Gaydos]

Submitted: 2019-09-24 08:44:51;   Last Modified: 2020-08-03 05:49:56.
Printed from the PrimePages <primes.utm.edu> © G. L. Honaker and Chris K. Caldwell