11187...99999 (72-digits)

This number is a prime.

                                                                          11
1871110514 8623584429 1898596971 6214110926 1587087232 2047999999 9999999999

The product of first 35 triangular numbers (1 through 630) minus 1 is the largest prime number less than a googol of this type. [Gupta]