644450432 has 64 divisors (see below), whose sum is σ = 1345420800. Its totient is φ = 306898944.

The previous prime is 644450419. The next prime is 644450449. The reversal of 644450432 is 234054446.

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1345169 + ... + 1345647.

It is an arithmetic number, because the mean of its divisors is an integer number (21022200).

Almost surely, 2^644450432 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 644450432, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (672710400).

644450432 is an abundant number, since it is smaller than the sum of its proper divisors (700970368).

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

644450432 is a wasteful number, since it uses less digits than its factorization.

644450432 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 973 (or 961 counting only the distinct ones).

The product of its (nonzero) digits is 46080, while the sum is 32.

The square root of 644450432 is about 25386.0282832900. The cubic root of 644450432 is about 863.7667980590.

The spelling of 644450432 in words is "six hundred forty-four million, four hundred fifty thousand, four hundred thirty-two".