393

This number is a composite.

+ 1000^393 - 393 is prime. Note that 393 is the second and largest known number with this property. [Firoozbakht]

+ The smallest semiprime formed by inserting a semiprime between the semiprime's ordered factors. Can you find a large example?

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