47142...76857 (46-digits)

This number is a prime.

                          471423 2143423142 5345234567 4657564765 4758676857

The smallest prime made up from a double-digit prime, (47), followed from the concatenation in order of all the primes each consisting of four successive digits, i.e., 1423, 2143, 4231, 4253, 4523, 4567, 4657, 5647, 6547, 5867, 6857. [Loungrides]