This number is a prime.

                                                        112233445 5667788991

Just showing those entries submitted by 'Silva': (Click here to show all)

+ Place 1 after the concatenation of the 9 digits duplicated and obtain a 19-digit prime, whose sum of digits is the 91 appearing the end of the prime. [Silva]

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