644720382 has 24 divisors (see below), whose sum is σ = 1402059360. Its totient is φ = 214112160.

The previous prime is 644720347. The next prime is 644720387. The reversal of 644720382 is 283027446.

644720382 is a `hidden beast` number, since 6 + 447 + 203 + 8 + 2 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644720387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 61207 + ... + 70962.

It is an arithmetic number, because the mean of its divisors is an integer number (58419140).

Almost surely, 2^644720382 is an apocalyptic number.

644720382 is an abundant number, since it is smaller than the sum of its proper divisors (757338978).

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

644720382 is a wasteful number, since it uses less digits than its factorization.

644720382 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 132448 (or 132445 counting only the distinct ones).

The product of its (nonzero) digits is 64512, while the sum is 36.

The square root of 644720382 is about 25391.3446276482. The cubic root of 644720382 is about 863.8873872647.

The spelling of 644720382 in words is "six hundred forty-four million, seven hundred twenty thousand, three hundred eighty-two".