72173...17999 (83-digits)

This number is a prime.

                                                              721 7373655299
6866735119 7964859567 6894599937 1377377779 7133337931 7179713397 1739117999

Just showing those entries submitted by 'Rivera': (Click here to show all)

A bi-truncatable prime, i.e., in each step the leftmost and the rightmost digits are simultaneously eliminated. [Rivera]