640663166 has 32 divisors (see below), whose sum is σ = 1188432000. Its totient is φ = 254659680.

The previous prime is 640663141. The next prime is 640663189. The reversal of 640663166 is 661366046.

It is a Harshad number since it is a multiple of its sum of digits (38).

It is a congruent number.

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, 53516 + ... + 64383.

It is an arithmetic number, because the mean of its divisors is an integer number (37138500).

Almost surely, 2^640663166 is an apocalyptic number.

640663166 is a deficient number, since it is larger than the sum of its proper divisors (547768834).

640663166 is a wasteful number, since it uses less digits than its factorization.

640663166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 117944.

The product of its (nonzero) digits is 93312, while the sum is 38.

The square root of 640663166 is about 25311.3248566724. The cubic root of 640663166 is about 862.0714290610.

The spelling of 640663166 in words is "six hundred forty million, six hundred sixty-three thousand, one hundred sixty-six".