640836520 has 32 divisors (see below), whose sum is σ = 1447002720. Its totient is φ = 255424320.

The previous prime is 640836499. The next prime is 640836523. The reversal of 640836520 is 25638046.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (640836523) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16986 + ... + 39625.

It is an arithmetic number, because the mean of its divisors is an integer number (45218835).

Almost surely, 2^640836520 is an apocalyptic number.

It is an amenable number.

640836520 is an abundant number, since it is smaller than the sum of its proper divisors (806166200).

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

640836520 is a wasteful number, since it uses less digits than its factorization.

640836520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56905 (or 56901 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 34.

The square root of 640836520 is about 25314.7490605773. The cubic root of 640836520 is about 862.1491766520.

The spelling of 640836520 in words is "six hundred forty million, eight hundred thirty-six thousand, five hundred twenty".