640443660 has 48 divisors (see below), whose sum is σ = 1795218432. Its totient is φ = 170596800.

The previous prime is 640443649. The next prime is 640443689. The reversal of 640443660 is 66344046.

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, 54075 + ... + 64845.

It is an arithmetic number, because the mean of its divisors is an integer number (37400384).

Almost surely, 2^640443660 is an apocalyptic number.

640443660 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

640443660 is an abundant number, since it is smaller than the sum of its proper divisors (1154774772).

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

640443660 is a wasteful number, since it uses less digits than its factorization.

640443660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11774 (or 11772 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 33.

The square root of 640443660 is about 25306.9883629009. The cubic root of 640443660 is about 861.9729626194.

The spelling of 640443660 in words is "six hundred forty million, four hundred forty-three thousand, six hundred sixty".