644046256 has 40 divisors (see below), whose sum is σ = 1431470880. Its totient is φ = 274980864.

The previous prime is 644046209. The next prime is 644046259. The reversal of 644046256 is 652640446.

644046256 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (644046259) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19440 + ... + 40816.

It is an arithmetic number, because the mean of its divisors is an integer number (35786772).

Almost surely, 2^644046256 is an apocalyptic number.

It is an amenable number.

644046256 is an abundant number, since it is smaller than the sum of its proper divisors (787424624).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644046256 is a wasteful number, since it uses less digits than its factorization.

644046256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21661 (or 21655 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 37.

The square root of 644046256 is about 25378.0664354084. The cubic root of 644046256 is about 863.5861858654.

The spelling of 644046256 in words is "six hundred forty-four million, forty-six thousand, two hundred fifty-six".