51631 has 2 divisors, whose sum is σ = 51632. Its totient is φ = 51630.

The previous prime is 51613. The next prime is 51637. The reversal of 51631 is 13615.

Together with previous prime (51613) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 51631 - 2⁵ = 51599 is a prime.

It is a super-2 number, since 2×51631² = 5331520322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (51637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 25815 + 25816.

It is an arithmetic number, because the mean of its divisors is an integer number (25816).

2⁵¹⁶³¹ is an apocalyptic number.

51631 is a deficient number, since it is larger than the sum of its proper divisors (1).

51631 is an equidigital number, since it uses as much as digits as its factorization.

51631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 90, while the sum is 16.

The square root of 51631 is about 227.2245585319. The cubic root of 51631 is about 37.2366136606.

Subtracting from 51631 its sum of digits (16), we obtain a palindrome (51615).

The spelling of 51631 in words is "fifty-one thousand, six hundred thirty-one".