631521 has 12 divisors (see below), whose sum is σ = 995280. Its totient is φ = 382680.

The previous prime is 631513. The next prime is 631529. The reversal of 631521 is 125136.

It is an interprime number because it is at equal distance from previous prime (631513) and next prime (631529).

It is not a de Polignac number, because 631521 - 2³ = 631513 is a prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 631494 and 631503.

It is not an unprimeable number, because it can be changed into a prime (631529) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3091 + ... + 3288.

It is an arithmetic number, because the mean of its divisors is an integer number (82940).

2⁶³¹⁵²¹ is an apocalyptic number.

It is an amenable number.

631521 is a deficient number, since it is larger than the sum of its proper divisors (363759).

631521 is a wasteful number, since it uses less digits than its factorization.

631521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6396 (or 6393 counting only the distinct ones).

The product of its digits is 180, while the sum is 18.

The square root of 631521 is about 794.6829556496. The cubic root of 631521 is about 85.7951225486.

Adding to 631521 its reverse (125136), we get a palindrome (756657).

It can be divided in two parts, 6315 and 21, that added together give a palindrome (6336).

The spelling of 631521 in words is "six hundred thirty-one thousand, five hundred twenty-one".