This number is a prime.

+ 19 is prime, 1099 is composite, 100999 is prime, 10009999 is composite, 1000099999 is prime, 100000999999 is composite. Unfortunately, the next three terms in this sequence are each composite and then we have 10000000009999999999 is prime. [Nwamba]

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