521401636 has 12 divisors (see below), whose sum is σ = 1042803328. Its totient is φ = 223457832.

The previous prime is 521401631. The next prime is 521401637. The reversal of 521401636 is 636104125.

521401636 is an admirable number.

It is a Harshad number since it is a multiple of its sum of digits (28), and also a Moran number because the ratio is a prime number: 18621487 = 521401636 / (5 + 2 + 1 + 4 + 0 + 1 + 6 + 3 + 6).

It is not an unprimeable number, because it can be changed into a prime (521401631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9310716 + ... + 9310771.

Almost surely, 2^521401636 is an apocalyptic number.

It is an amenable number.

521401636 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

521401636 is a wasteful number, since it uses less digits than its factorization.

521401636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18621498 (or 18621496 counting only the distinct ones).

The product of its (nonzero) digits is 4320, while the sum is 28.

The square root of 521401636 is about 22834.2207224157. The cubic root of 521401636 is about 804.8670155696.

The spelling of 521401636 in words is "five hundred twenty-one million, four hundred one thousand, six hundred thirty-six".