12340...04321 (6939-digits)

This number is a probable-prime (likely to be a prime but we have not (re-)proven it on this site).

The largest titanic palindromic prime (less than a gigantic prime) of the form 1234*10^(k + 4) + 4321 (for k = 6931), where k is the number of zeros between 1234 and 4321. [Gupta]