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