640464666 has 16 divisors (see below), whose sum is σ = 1281633600. Its totient is φ = 213370848.

The previous prime is 640464637. The next prime is 640464679. The reversal of 640464666 is 666464046.

640464666 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17131 + ... + 39678.

It is an arithmetic number, because the mean of its divisors is an integer number (80102100).

Almost surely, 2^640464666 is an apocalyptic number.

640464666 is an abundant number, since it is smaller than the sum of its proper divisors (641168934).

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

640464666 is a wasteful number, since it uses less digits than its factorization.

640464666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 58693.

The product of its (nonzero) digits is 497664, while the sum is 42.

The square root of 640464666 is about 25307.4033831999. The cubic root of 640464666 is about 861.9823865064.

The spelling of 640464666 in words is "six hundred forty million, four hundred sixty-four thousand, six hundred sixty-six".