644483840 has 288 divisors, whose sum is σ = 2076834816. Its totient is φ = 185057280.

The previous prime is 644483837. The next prime is 644483863. The reversal of 644483840 is 48384446.

It is a super-2 number, since 2×644483840² = 830718840042291200, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1281029 + ... + 1281531.

It is an arithmetic number, because the mean of its divisors is an integer number (7211232).

Almost surely, 2^644483840 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 644483840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1038417408).

644483840 is an abundant number, since it is smaller than the sum of its proper divisors (1432350976).

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

644483840 is a wasteful number, since it uses less digits than its factorization.

644483840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 555 (or 541 counting only the distinct ones).

The product of its (nonzero) digits is 294912, while the sum is 41.

The square root of 644483840 is about 25386.6862745022. The cubic root of 644483840 is about 863.7817235527.

It can be divided in two parts, 644 and 483840, that added together give a palindrome (484484).

The spelling of 644483840 in words is "six hundred forty-four million, four hundred eighty-three thousand, eight hundred forty".