91111...11119 (247-digits)

This number is a prime.

                                    9111111 1111111111 1111111111 1111111111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111111
1111111111 1111111111 1111111111 1111111111 1111111111 1111111111 1111111119

Just showing those entries submitted by 'Caldwell': (Click here to show all)

8*10²⁴⁶+(10²⁴⁷-1)/9+8 was the largest known depression prime in 1991. [Caldwell]