10000...00001 (29-digits)

This number is a prime.

                                             100000000 0100010001 0000000001

If you multiply the palindromic prime 10000000001000100010000000001 by any of the following palprimes 757, 787, 797, 919, 929 13931, 15551, 16561, 16661, or 17471, you get a palindrome. Found by Jim Howell, 1999. [Rivera]