644970008 has 32 divisors (see below), whose sum is σ = 1227878400. Its totient is φ = 317574432.

The previous prime is 644969993. The next prime is 644970031. The reversal of 644970008 is 800079446.

It is a happy number.

It is a super-4 number, since 4×644970008⁴ (a number of 36 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent 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, 138941 + ... + 143507.

It is an arithmetic number, because the mean of its divisors is an integer number (38371200).

Almost surely, 2^644970008 is an apocalyptic number.

It is an amenable number.

644970008 is a deficient number, since it is larger than the sum of its proper divisors (582908392).

644970008 is a wasteful number, since it uses less digits than its factorization.

644970008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4839 (or 4835 counting only the distinct ones).

The product of its (nonzero) digits is 48384, while the sum is 38.

The square root of 644970008 is about 25396.2597246130. The cubic root of 644970008 is about 863.9988675968.

The spelling of 644970008 in words is "six hundred forty-four million, nine hundred seventy thousand, eight".