11728...68481 (176-digits)

This number is a prime.

                                     117289 4913835211 4198572413 7569410338
6736975757 4411185878 7649720159 9390044934 2718963076 3358262223 7229761990
4578032905 9371683778 2655940092 9286242305 1509815793 4866119187 5666868481

If we concatenate the first 17 powers of 17, we obtain a prime number with 176 digits! [Hartley]