644886324 has 18 divisors (see below), whose sum is σ = 1630129410. Its totient is φ = 214962096.

The previous prime is 644886317. The next prime is 644886329. The reversal of 644886324 is 423688446.

644886324 is a `hidden beast` number, since 6 + 4 + 4 + 8 + 8 + 632 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 498718224 + 146168100 = 22332^2 + 12090^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 644886324.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644886329) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8956719 + ... + 8956790.

It is an arithmetic number, because the mean of its divisors is an integer number (90562745).

Almost surely, 2^644886324 is an apocalyptic number.

It is an amenable number.

644886324 is an abundant number, since it is smaller than the sum of its proper divisors (985243086).

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

644886324 is a wasteful number, since it uses less digits than its factorization.

644886324 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17913519 (or 17913514 counting only the distinct ones).

The product of its digits is 884736, while the sum is 45.

The square root of 644886324 is about 25394.6121057204. The cubic root of 644886324 is about 863.9614984129.

The spelling of 644886324 in words is "six hundred forty-four million, eight hundred eighty-six thousand, three hundred twenty-four".