19

This number is a prime.

Just showing those entries submitted by 'De Geest': (Click here to show all)

19⁵ + 19² + 19¹ + 19³ + 19⁵ + 19⁶ + 19⁴ + 19⁰ = 52135640. [De Geest]

19 divides its following consecutive concatenated composite numbers (202122). [De Geest]

Inserting seventeen zeros between the two digits of 19 makes another prime of exactly 19 digits. Note that seventeen and 19 are twin primes. [De Geest]

19 divides the concatenation of the integers from 19 down to 1. [De Geest]

19 is the smallest super-2 number, i.e., an integer n such that 2n^2 contains 2 consecutive 2s in its decimal representation. [De Geest]