11933...33911 (41-digits)

This number is a prime.

                               1 1933316181 5121713302 0331712151 8161333911

2
30203
133020331
1713302033171
12171330203317121
151217133020331712151
1815121713302033171215181
16181512171330203317121518161
331618151217133020331712151816133
9333161815121713302033171215181613339
11933316181512171330203317121518161333911

The largest palindromic prime in a palindromic prime pyramid of step size two, where each palindromic prime is the smallest palindromic prime that contains the palindromic prime in the row above. Note that "11" mysteriously appears on the ends of row 11, reminding us that all palindromic numbers greater than 11, containing an even number of digits, are divisible by 11. (See August 2007 issue of Sciences et Avenir, p.72.)