99999...77777 (281-digits)

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

                                                                           9
9999999999 9999999999 9999999999 9999999999 9999999999 9999999999 9999999999
9999999999 8888888888 8888888888 8888888888 8888888888 8888888888 8888888888
8888555555 5555555555 5555555551 3333333336 6666666666 6666666666 6666666666
6666644444 4444444444 4777777777 7777777777 7777777777 7777777777 7777777777

+ Starting with the "most distinct digits prime" you can obtain two automorphic primes using the rule "d digits of each digit d" twice in cascade: 985130647 -> 9999999998888888855555133366666644447777777 -> etc. [Rivera]

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