10000...00019 (91-digits)

This number is a prime.

                                                     1 0000191000 0201000021
1000022100 0023100002 4100002510 0002410000 2310000221 0000211000 0201000019

The smallest prime formed from the concatenation of n consecutive n-digit composite numbers in the pattern {a, b, c, d, e, f, g, f, e, d, c, b, a}, i.e., {1000019, 1000020, 1000021, 1000022, 1000023, 1000024, 1000025, 1000024, 1000023, 1000022, 1000021, 1000020, 1000019}, (case n=7). [Bajpai]