19008...65571 (97-digits)

This number is a prime.

                                               1900871 2816648221 1312685157
3935413975 4718967899 6851549366 6638539088 0271038021 0449895719 1261465571

The largest prime factor for the RSA challenge number RSA-640. Discovered by F. Bahr, et al., on November 2, 2005. [Sladcik]