79787...32221 (118-digits)

This number is a prime.

                        79787776 7574737271 7069686766 6564636261 6059585756
5554535251 5049484746 4544434241 4039383736 3534333231 3029282726 2524232221

The largest concatenation (in descending order) of n consecutive double-digit integers (n = 59). [Loungrides]