636401644 has 12 divisors (see below), whose sum is σ = 1130325784. Its totient is φ = 313451424.

The previous prime is 636401639. The next prime is 636401657. The reversal of 636401644 is 446104636.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1187049 + ... + 1187584.

Almost surely, 2^636401644 is an apocalyptic number.

It is an amenable number.

636401644 is a deficient number, since it is larger than the sum of its proper divisors (493924140).

636401644 is a wasteful number, since it uses less digits than its factorization.

636401644 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2374704 (or 2374702 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 34.

The square root of 636401644 is about 25227.0022793038. The cubic root of 636401644 is about 860.1557514914.

The spelling of 636401644 in words is "six hundred thirty-six million, four hundred one thousand, six hundred forty-four".