640392 has 16 divisors (see below), whose sum is σ = 1601040. Its totient is φ = 213456.

The previous prime is 640369. The next prime is 640411. The reversal of 640392 is 293046.

It is a Harshad number since it is a multiple of its sum of digits (24), and also a Moran number because the ratio is a prime number: 26683 = 640392 / (6 + 4 + 0 + 3 + 9 + 2).

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 640392.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13318 + ... + 13365.

It is an arithmetic number, because the mean of its divisors is an integer number (100065).

2⁶⁴⁰³⁹² is an apocalyptic number.

It is an amenable number.

640392 is an abundant number, since it is smaller than the sum of its proper divisors (960648).

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

640392 is a wasteful number, since it uses less digits than its factorization.

640392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26692 (or 26688 counting only the distinct ones).

The product of its (nonzero) digits is 1296, while the sum is 24.

The square root of 640392 is about 800.2449624959. The cubic root of 640392 is about 86.1949785602.

The spelling of 640392 in words is "six hundred forty thousand, three hundred ninety-two".