21971...42781 (37-digits)

This number is a prime.

                                    2197172 8133110007 2951234321 6125642781

The reverse concatenation of the first emirp number n of cubes of successive numbers is prime, (case n=13), i.e., 2197=13^3, 1728=12^3, 1331=11^3, … , 27=3^3, 8=2^3, 1=1^3. [Loungrides]