99797...37177 (131-digits)

This number is a prime.

         9 9797796794 7937907887 8778578277 9778775772 7677647617 6075875775
5754748746 7457397367 3473373173 0727725722 7197167157 1371271079 7674737177

The only prime formed from the concatenation in reverse order of all the primes less than a thousand ending with the same digit d, (case d=7). [Loungrides]