521631864 has 96 divisors (see below), whose sum is σ = 1530328800. Its totient is φ = 159563520.

The previous prime is 521631841. The next prime is 521631941. The reversal of 521631864 is 468136125.

It is a happy number.

521631864 is a `hidden beast` number, since 521 + 63 + 18 + 64 = 666.

It is a super-2 number, since 2×521631864² = 544199603080228992, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 167877 + ... + 170955.

It is an arithmetic number, because the mean of its divisors is an integer number (15940925).

Almost surely, 2^521631864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 521631864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (765164400).

521631864 is an abundant number, since it is smaller than the sum of its proper divisors (1008696936).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

521631864 is a wasteful number, since it uses less digits than its factorization.

521631864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3285 (or 3278 counting only the distinct ones).

The product of its digits is 34560, while the sum is 36.

The square root of 521631864 is about 22839.2614591628. The cubic root of 521631864 is about 804.9854627469.

Adding to 521631864 its reverse (468136125), we get a palindrome (989767989).

The spelling of 521631864 in words is "five hundred twenty-one million, six hundred thirty-one thousand, eight hundred sixty-four".