644540056 has 16 divisors (see below), whose sum is σ = 1208928240. Its totient is φ = 322159200.

The previous prime is 644540033. The next prime is 644540077. The reversal of 644540056 is 650045446.

644540056 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14205 + ... + 38611.

It is an arithmetic number, because the mean of its divisors is an integer number (75558015).

Almost surely, 2^644540056 is an apocalyptic number.

It is an amenable number.

644540056 is a deficient number, since it is larger than the sum of its proper divisors (564388184).

644540056 is a wasteful number, since it uses less digits than its factorization.

644540056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27714 (or 27710 counting only the distinct ones).

The product of its (nonzero) digits is 57600, while the sum is 34.

The square root of 644540056 is about 25387.7934448821. The cubic root of 644540056 is about 863.8068376769.

The spelling of 644540056 in words is "six hundred forty-four million, five hundred forty thousand, fifty-six".