644360 has 32 divisors (see below), whose sum is σ = 1474200. Its totient is φ = 253440.

The previous prime is 644359. The next prime is 644363. The reversal of 644360 is 63446.

It can be written as a sum of positive squares in 4 ways, for example, as 206116 + 438244 = 454^2 + 662^2 .

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 7 ways as a sum of consecutive naturals, for example, 3470 + ... + 3650.

2⁶⁴⁴³⁶⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644360, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (737100).

644360 is an abundant number, since it is smaller than the sum of its proper divisors (829840).

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

644360 is a wasteful number, since it uses less digits than its factorization.

644360 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281 (or 277 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 23.

The square root of 644360 is about 802.7203747258. The cubic root of 644360 is about 86.3726393704.

The spelling of 644360 in words is "six hundred forty-four thousand, three hundred sixty".