644335232 has 16 divisors (see below), whose sum is σ = 1283636850. Its totient is φ = 322167552.

The previous prime is 644335229. The next prime is 644335261. The reversal of 644335232 is 232533446.

It can be written as a sum of positive squares in only one way, i.e., 431642176 + 212693056 = 20776^2 + 14584^2 .

It is a tau number, because it is divible by the number of its divisors (16).

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2516807 + ... + 2517062.

Almost surely, 2^644335232 is an apocalyptic number.

It is an amenable number.

644335232 is a deficient number, since it is larger than the sum of its proper divisors (639301618).

644335232 is an equidigital number, since it uses as much as digits as its factorization.

644335232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5033883 (or 5033871 counting only the distinct ones).

The product of its digits is 51840, while the sum is 32.

The square root of 644335232 is about 25383.7592172633. The cubic root of 644335232 is about 863.7153268830.

Adding to 644335232 its reverse (232533446), we get a palindrome (876868678).

The spelling of 644335232 in words is "six hundred forty-four million, three hundred thirty-five thousand, two hundred thirty-two".