640955636 has 6 divisors (see below), whose sum is σ = 1121672370. Its totient is φ = 320477816.

The previous prime is 640955629. The next prime is 640955669. The reversal of 640955636 is 636559046.

It can be written as a sum of positive squares in only one way, i.e., 545502736 + 95452900 = 23356^2 + 9770^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80119451 + ... + 80119458.

It is an arithmetic number, because the mean of its divisors is an integer number (186945395).

Almost surely, 2^640955636 is an apocalyptic number.

It is an amenable number.

640955636 is a deficient number, since it is larger than the sum of its proper divisors (480716734).

640955636 is a wasteful number, since it uses less digits than its factorization.

640955636 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160238913 (or 160238911 counting only the distinct ones).

The product of its (nonzero) digits is 583200, while the sum is 44.

The square root of 640955636 is about 25317.1016508604. The cubic root of 640955636 is about 862.2025908983.

The spelling of 640955636 in words is "six hundred forty million, nine hundred fifty-five thousand, six hundred thirty-six".