644243488 has 144 divisors (see below), whose sum is σ = 1585350144. Its totient is φ = 252149760.

The previous prime is 644243477. The next prime is 644243503. The reversal of 644243488 is 884342446.

It is a super-2 number, since 2×644243488² = 830099343660812288, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2506656 + ... + 2506912.

It is an arithmetic number, because the mean of its divisors is an integer number (11009376).

Almost surely, 2^644243488 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 644243488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (792675072).

644243488 is an abundant number, since it is smaller than the sum of its proper divisors (941106656).

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

644243488 is a wasteful number, since it uses less digits than its factorization.

644243488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 343 (or 316 counting only the distinct ones).

The product of its digits is 589824, while the sum is 43.

The square root of 644243488 is about 25381.9520131924. The cubic root of 644243488 is about 863.6743314217.

The spelling of 644243488 in words is "six hundred forty-four million, two hundred forty-three thousand, four hundred eighty-eight".