640164 has 24 divisors (see below), whose sum is σ = 1707328. Its totient is φ = 182880.

The previous prime is 640163. The next prime is 640193. The reversal of 640164 is 461046.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a self number, because there is not a number n which added to its sum of digits gives 640164.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640164.

It is not an unprimeable number, because it can be changed into a prime (640163) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3727 + ... + 3894.

2⁶⁴⁰¹⁶⁴ is an apocalyptic number.

It is an amenable number.

640164 is an abundant number, since it is smaller than the sum of its proper divisors (1067164).

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

640164 is a wasteful number, since it uses less digits than its factorization.

640164 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7635 (or 7633 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 640164 is about 800.1024934344. The cubic root of 640164 is about 86.1847479578.

The spelling of 640164 in words is "six hundred forty thousand, one hundred sixty-four".