9551

This number is a prime.

Compare 9551 with the 9551st prime. [Punches]

The largest prime found in the following array:

 9 1 3 3
 1 5 8 3
 7 5 2 9
 3 9 1 1.

Every row, column, and main diagonal is a different emirp. Ignoring rotations, it is the only possible 4-by-4 prime magic square of this type.