11333...33311 (101-digits)

This number is a prime.

                                          1 1333331313 1311313313 1333313113
1331333311 1111313111 1131311111 1333313313 1131333313 1331311313 1313333311

A Carrousel palindromic prime: it remains palprime if you change all the digits according to this scheme: 1 ->3->7->9, producing three new palprimes. Found by Emmanuel Vantieghem. [Rivera]