29999...99999 (56-digits)

This number is a prime.

               299999 9999999999 9999999999 9999999999 9999999999 9999999999

The fifty-sixth term in the almost repunit sequence whose general nth term is given by 3*10^n-1 (here, n = 55) and constitutes the largest prime output in the sequence for n < 100. [Schiffman]