11111...11111 (51-digits)

This number is a prime.

                    1 1111111111 1211111212 2112421122 1211111211 1111111111

A palindromic prime such that the square of the SOD (Sum of Digits) is equal to the POD (Product of Digits), i.e., SOD=64=2^6 and POD=2^12. Found by J. C. Rosa, 2002. [Rivera]