521561640 has 64 divisors (see below), whose sum is σ = 1586145600. Its totient is φ = 137175552.

The previous prime is 521561597. The next prime is 521561641. The reversal of 521561640 is 46165125.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 521561598 and 521561607.

It is not an unprimeable number, because it can be changed into a prime (521561641) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21010 + ... + 38529.

It is an arithmetic number, because the mean of its divisors is an integer number (24783525).

Almost surely, 2^521561640 is an apocalyptic number.

It is an amenable number.

521561640 is an abundant number, since it is smaller than the sum of its proper divisors (1064583960).

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

521561640 is a wasteful number, since it uses less digits than its factorization.

521561640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 59626 (or 59622 counting only the distinct ones).

The product of its (nonzero) digits is 7200, while the sum is 30.

The square root of 521561640 is about 22837.7240547301. The cubic root of 521561640 is about 804.9493377579.

The spelling of 521561640 in words is "five hundred twenty-one million, five hundred sixty-one thousand, six hundred forty".