14000...00041 (47-digits)

This number is a prime.

                         1400000 0000000000 0000000000 0000000000 0000000041

The only known palindromic prime that begins with a number n, followed by prime(n) zeros and ends with the reversal of n. The next such prime (if it exists) will have more than 30000 digits. [Firoozbakht]