# 23

This number is a prime.

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

Kristen Eller ©2002 |

A factorial expression involving the digits of 23 is 1! + (2! + 2!) + (3! + 3! + 3!). [Capelle]

The smallest non-reflectable non-strobogrammatic non-invertible non-palindromic non-reversible prime number. [Capelle]

There are 23 known natural numbers n such that
2^{n} does not contain the digit
2. Their sum ends with 23, which is one of them. The prime
cases are easy to remember: 2, 3, 23 and ... the 23th
prime! [Capelle]

The largest known prime number that cannot be written as the sum of at most three powerful numbers. [Capelle]

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