55631 has 2 divisors, whose sum is σ = 55632. Its totient is φ = 55630.

The previous prime is 55621. The next prime is 55633. The reversal of 55631 is 13655.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55631 is a prime.

It is a super-2 number, since 2×55631² = 6189616322, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 55633, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27815 + 27816.

It is an arithmetic number, because the mean of its divisors is an integer number (27816).

2⁵⁵⁶³¹ is an apocalyptic number.

55631 is a deficient number, since it is larger than the sum of its proper divisors (1).

55631 is an equidigital number, since it uses as much as digits as its factorization.

55631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 450, while the sum is 20.

The square root of 55631 is about 235.8622479330. The cubic root of 55631 is about 38.1744060717.

Subtracting from 55631 its sum of digits (20), we obtain a triangular number (55611 = T₃₃₃).

It can be divided in two parts, 55 and 631, that added together give a palindrome (686).

The spelling of 55631 in words is "fifty-five thousand, six hundred thirty-one".