644364 has 36 divisors (see below), whose sum is σ = 1862224. Its totient is φ = 184032.

The previous prime is 644363. The next prime is 644377. The reversal of 644364 is 463446.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (644363) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1027 + ... + 1530.

2⁶⁴⁴³⁶⁴ is an apocalyptic number.

It is an amenable number.

644364 is an abundant number, since it is smaller than the sum of its proper divisors (1217860).

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

644364 is a wasteful number, since it uses less digits than its factorization.

644364 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2574 (or 2569 counting only the distinct ones).

The product of its digits is 6912, while the sum is 27.

The square root of 644364 is about 802.7228662496. The cubic root of 644364 is about 86.3728180954.

The spelling of 644364 in words is "six hundred forty-four thousand, three hundred sixty-four".