70374...47307 (151-digits)

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

                                                                7 0374674172
7317345130 3051453411 3214211314 1102129105 1711351091 0510712410 5102220150
1421701501 9015311715 0192120114 1311241231 1435415030 3154371372 7147647307

The bottom row of a palindromic prime pyramid (starting with 2) of step size 3 and height 26, where each palindromic prime p is the smallest p that contains p in the row above. Note that the number of digits (151) is also a palindromic prime.