631531 has 2 divisors, whose sum is σ = 631532. Its totient is φ = 631530.

The previous prime is 631529. The next prime is 631537. The reversal of 631531 is 135136.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 631531 - 2¹ = 631529 is a prime.

It is a super-2 number, since 2×631531² = 797662807922, which contains 22 as substring.

Together with 631529, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 631499 and 631508.

It is not a weakly prime, because it can be changed into another prime (631537) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 315765 + 315766.

It is an arithmetic number, because the mean of its divisors is an integer number (315766).

2⁶³¹⁵³¹ is an apocalyptic number.

631531 is a deficient number, since it is larger than the sum of its proper divisors (1).

631531 is an equidigital number, since it uses as much as digits as its factorization.

631531 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 270, while the sum is 19.

The square root of 631531 is about 794.6892474420. The cubic root of 631531 is about 85.7955753954.

Adding to 631531 its reverse (135136), we get a palindrome (766667).

The spelling of 631531 in words is "six hundred thirty-one thousand, five hundred thirty-one".