99999...99991 (1049-digits)

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

A titanic automorphic prime Q produced by another 149-digit prime P = 999994999 9999999999 4499999419 4499994949 4499994949 9999949444 4444144999 4991944499 9494499949 9994994494 9949494999 9944494994 4449944994 9499499499 9499999991 by applying the following rule: substitute each digit d by d times such digit. Both primes P and Q and the quantity of digits of P and Q are composed by the squares of the digits 0, 1, 2 and 3. [Rivera]