644040004 has 24 divisors (see below), whose sum is σ = 1203552000. Its totient is φ = 300884640.

The previous prime is 644039927. The next prime is 644040011. The reversal of 644040004 is 400040446.

It is a happy number.

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, 85954 + ... + 93145.

It is an arithmetic number, because the mean of its divisors is an integer number (50148000).

Almost surely, 2^644040004 is an apocalyptic number.

It is an amenable number.

644040004 is a deficient number, since it is larger than the sum of its proper divisors (559511996).

644040004 is a wasteful number, since it uses less digits than its factorization.

644040004 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 179163 (or 179161 counting only the distinct ones).

The product of its (nonzero) digits is 1536, while the sum is 22.

The square root of 644040004 is about 25377.9432578765. The cubic root of 644040004 is about 863.5833914707.

The spelling of 644040004 in words is "six hundred forty-four million, forty thousand, four".