644004632 has 16 divisors (see below), whose sum is σ = 1213833600. Its totient is φ = 320315680.

The previous prime is 644004629. The next prime is 644004637. The reversal of 644004632 is 236400446.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 644004595 and 644004604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644004637) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 209207 + ... + 212262.

It is an arithmetic number, because the mean of its divisors is an integer number (75864600).

Almost surely, 2^644004632 is an apocalyptic number.

It is an amenable number.

644004632 is a deficient number, since it is larger than the sum of its proper divisors (569828968).

644004632 is a wasteful number, since it uses less digits than its factorization.

644004632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 421666 (or 421662 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 29.

The square root of 644004632 is about 25377.2463439200. The cubic root of 644004632 is about 863.5675812566.

The spelling of 644004632 in words is "six hundred forty-four million, four thousand, six hundred thirty-two".