61169616096168161861

This number is a prime.

                                                       6116961609 6168161861

{61169616096168161861, 61861616816160961169} is the smallest pair of 20-digit invertible-digit primes formed by concatenating in ascending and descending order four 5-digit consecutive invertible primes, i.e., {61169, 61609, 61681, 61861}. [Bajpai]