640936626 has 32 divisors (see below), whose sum is σ = 1409101056. Its totient is φ = 192738000.

The previous prime is 640936619. The next prime is 640936649. The reversal of 640936626 is 626639046.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28420 + ... + 45711.

It is an arithmetic number, because the mean of its divisors is an integer number (44034408).

Almost surely, 2^640936626 is an apocalyptic number.

640936626 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

640936626 is an abundant number, since it is smaller than the sum of its proper divisors (768164430).

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

640936626 is a wasteful number, since it uses less digits than its factorization.

640936626 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74278.

The product of its (nonzero) digits is 279936, while the sum is 42.

The square root of 640936626 is about 25316.7262101560. The cubic root of 640936626 is about 862.1940668381.

The spelling of 640936626 in words is "six hundred forty million, nine hundred thirty-six thousand, six hundred twenty-six".