2221771
This number is a prime.
The smallest prime 2221771 that remains prime for D=4 to 9
in 2D2D2D1D7D7D1. The primes thus obtained are:
2424241474741, 2525251575751, 2626261676761, 2727271777771,
2828281878781, 2929291979791. [Bajpai]
Printed from the PrimePages <t5k.org> © G. L. Honaker and Chris K. Caldwell