309427398372577

This number is a prime.

                                                            30942 7398372577

The smallest odd prime that is the sum of the first k primes in the following sequence: a(1) = 2; for n>=1, a(n+1) is the smallest palindromic prime with a(n) as a central substring, i.e., 309427398372577 = 2 + 727 + 37273 + 333727333 + 93337273339 + 309333727333903.