2777

This number is a prime.

2777 = 12 + 23 + 35 + 47 + 511 + 613 + 717 + 819, where each addend is the concatenation of n and the nth prime. (2777 is the smallest prime formed in this manner.) [Poo Sung]

Inserting this prime in-between two reversals of p^n we find the reversal of another power of p, i.e., 2^4=16, 2^24=16777216 (case p=2, n=4), and R(2^24)=61277761. [Loungrides]

The so-called “doomsday argument” holds that there is a 50% chance that the end of human life will come before the year 2777.