640172 has 18 divisors (see below), whose sum is σ = 1214388. Its totient is φ = 295152.

The previous prime is 640163. The next prime is 640193. The reversal of 640172 is 271046.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640172.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 203 + ... + 1149.

It is an arithmetic number, because the mean of its divisors is an integer number (67466).

2⁶⁴⁰¹⁷² is an apocalyptic number.

It is an amenable number.

640172 is a deficient number, since it is larger than the sum of its proper divisors (574216).

640172 is a wasteful number, since it uses less digits than its factorization.

640172 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 977 (or 962 counting only the distinct ones).

The product of its (nonzero) digits is 336, while the sum is 20.

The square root of 640172 is about 800.1074927783. The cubic root of 640172 is about 86.1851069674.

The spelling of 640172 in words is "six hundred forty thousand, one hundred seventy-two".