640636563 has 16 divisors (see below), whose sum is σ = 980266496. Its totient is φ = 364556160.

The previous prime is 640636561. The next prime is 640636567. The reversal of 640636563 is 365636046.

It is a happy number.

It is not a de Polignac number, because 640636563 - 2¹ = 640636561 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (640636561) 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, 58231 + ... + 68352.

It is an arithmetic number, because the mean of its divisors is an integer number (61266656).

Almost surely, 2^640636563 is an apocalyptic number.

640636563 is a deficient number, since it is larger than the sum of its proper divisors (339629933).

640636563 is a wasteful number, since it uses less digits than its factorization.

640636563 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126834.

The product of its (nonzero) digits is 233280, while the sum is 39.

The square root of 640636563 is about 25310.7993354615. The cubic root of 640636563 is about 862.0594966318.

The spelling of 640636563 in words is "six hundred forty million, six hundred thirty-six thousand, five hundred sixty-three".