99999989

This number is a prime.

+ According to Oliver Sacks, no practically realizable algorithm has yet been invented for rapidly identifying primes in excess of 99999989 as apparently performed by the autistic twins that he observed.

+

The largest 8-digit prime is a member of a set of four primes, each of which has a maximum sum of digits. 89999999
99899999
99998999
99999989
[Green]

+ The largest prime serial number on a U.S. Bill. It is currently in the possession of Dave Undis of CoolSerialNumbers.com.

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