644561152 has 36 divisors (see below), whose sum is σ = 1298684016. Its totient is φ = 319255040.

The previous prime is 644561129. The next prime is 644561227. The reversal of 644561152 is 251165446.

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, 15627 + ... + 39157.

It is an arithmetic number, because the mean of its divisors is an integer number (36074556).

Almost surely, 2^644561152 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 644561152, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (649342008).

644561152 is an abundant number, since it is smaller than the sum of its proper divisors (654122864).

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

644561152 is a wasteful number, since it uses less digits than its factorization.

644561152 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23654 (or 23640 counting only the distinct ones).

The product of its digits is 28800, while the sum is 34.

The square root of 644561152 is about 25388.2089167393. The cubic root of 644561152 is about 863.8162617978.

The spelling of 644561152 in words is "six hundred forty-four million, five hundred sixty-one thousand, one hundred fifty-two".