141

This number is a composite.

n x 2ⁿ + 1 is a Cullen prime if n = 141. The largest known case if n is palindromic.

A lucky number indexed by a prime number. [De Geest]

The smallest of the only two numbers n such that each of n, n+1, n+2, n+3, n+4, n+5, n+6 and n+7 have exactly two distinct prime factors. [Gudipati]