44441...99999 (157-digits)

This number is a prime.

                                                          4444105 4973306739
3722377327 8869842880 5102842030 6579149850 4426852153 2190472966 6264804483
1617912215 1564882713 2956320113 1345294533 8531839999 9999999999 9999999999

In late 2003, Professor W. Edwin Clark of the University of South Florida discovered that (100!-21)/21 is prime. [Dobb]