71

Number
$71$ (seventy-one) is:


 * The $20$th prime number, after $2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67$


 * The $5$th emirp after $13, 17, 31, 37$.


 * The $2$nd prime number after $53$ which cannot be expressed as the difference between a power of $2$ and a power of $3$.