3467643 
An extraordinary find by Carlos Rivera [ Feb 13, 1999 ] He succeeded in amalgamating three concepts : the primes (from 3 to 29) the nine_digits (powers from right to left) the palindromes (the sum of the terms) 
= 3^{9} + 5^{8} + 7^{7} + 11^{6} + 13^{5} + 17^{4} + 19^{3} + 23^{2} + 29^{1}

