631591 has 6 divisors (see below), whose sum is σ = 654992. Its totient is φ = 609000.

The previous prime is 631583. The next prime is 631597. The reversal of 631591 is 195136.

631591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 631591 - 2³ = 631583 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (631597) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 466 + ... + 1216.

2⁶³¹⁵⁹¹ is an apocalyptic number.

631591 is a deficient number, since it is larger than the sum of its proper divisors (23401).

631591 is an equidigital number, since it uses as much as digits as its factorization.

631591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 809 (or 780 counting only the distinct ones).

The product of its digits is 810, while the sum is 25.

The square root of 631591 is about 794.7269971506. The cubic root of 631591 is about 85.7982923755.

The spelling of 631591 in words is "six hundred thirty-one thousand, five hundred ninety-one".