10911...11109 (27-digits)

This number is a prime.

                                               1091114 0040140440 1400111109

The smallest prime P formed from the concatenation of five consecutive tban numbers in the pattern {a, b, c, d, e, d, c, b, a}, i.e., {109, 111, 400, 401, 404, 401, 400, 111, 109}. Curiously, P is also expressible as the sum of two squares. [Bajpai]