91013...12547 (53-digits)

This number is a prime.

                  910 1323910159 1129103110 1419121037 2116114112 4315112547

Prime string of consecutive integers from 20 to 47 whereby the composite numbers are replaced by the sum of their prime factors {9}{10}...{25}{47}. Replacing the composites by the concatenation of these prime factors (counting multiplicity) yields yet another prime of length 80 or {2*2*5}{3*7}...{2*23}{47}. [De Geest]