5381

This number is a prime.

This prime can be expressed as the sum of squares of five consecutive primes, starting with 23. [Patterson]

5381 = p(p(p(p(p(p(p(p(1)))))))), where p(n) denotes the nth prime number. [Sahilm]

The number of photographs taken by Wilson Bentley (1865-1931) of snowflakes, using a photographic adapter with a borrowed microscope. [Harrison]

The 1835th positive integer that contains exactly one 1 is the reversal of 1835. [Gaydos]