5101

This number is a prime.

The only prime number less than a googol formed from the concatenation in order of first multiples of 5 following by 1, (case n=2). [Loungrides]

5101 is the concatenation of the lessers of the twin prime pairs (5, 7) and (101, 103). The concatenation of the greaters, 7 and 103, gives 7103 which is also prime. [Galliani]

The palindromic prime 1464641, which is the smallest palindromic prime with three fours, divides 5101!+1. [Galliani]