10407...29087 (386-digits)

This number is a probable-prime (likely to be a prime but we have not (re-)proven it on this site).

                                     104079 3219466439 9081925240 3273640855
3861526224 7266704805 3191123504 0360805967 3360298012 2394417323 2418484242
1613954281 0077913835 6624832346 4908139906 6056773207 6292412950 9389220345
7731833496 6158355047 2959420547 6898112116 9367714754 8478866962 5013844382
6029173234 8885311160 8285384165 8502825560 4666224831 8909188018 4706822220
3140521026 6984354887 3295802887 8050869736 1869007147 2071055570 3168729087

The smallest beast Mersenne prime. [Bajpai]