521631 has 18 divisors (see below), whose sum is σ = 829920. Its totient is φ = 315480.

The previous prime is 521603. The next prime is 521641. The reversal of 521631 is 136125.

It is not a de Polignac number, because 521631 - 2⁶ = 521567 is a prime.

It is a super-2 number, since 2×521631² = 544197800322, which contains 22 as substring.

521631 is a lucky number.

It is a zygodrome in base 3.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (521641) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 850 + ... + 1328.

2⁵²¹⁶³¹ is an apocalyptic number.

521631 is a deficient number, since it is larger than the sum of its proper divisors (308289).

521631 is a wasteful number, since it uses less digits than its factorization.

521631 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 507 (or 493 counting only the distinct ones).

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

The square root of 521631 is about 722.2402647319. The cubic root of 521631 is about 80.4985018303.

Adding to 521631 its reverse (136125), we get a palindrome (657756).

The spelling of 521631 in words is "five hundred twenty-one thousand, six hundred thirty-one".