This number is a prime.
When you remove the penultimate (next to the last) digit of 123457 you will end up with yet another prime. Repeat the process for four more primes. [Brod]
The smallest prime formed from the first six imperfect numbers in order. [Beedassy]
The sum of the repunit number 111111 and all truncations of itself plus one is prime. [Loungrides]
(There is one curio for this number that has not yet been approved by an editor.)
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell