644904366 has 32 divisors (see below), whose sum is σ = 1298903040. Its totient is φ = 213458784.

The previous prime is 644904329. The next prime is 644904373. The reversal of 644904366 is 663409446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 746851 + ... + 747713.

It is an arithmetic number, because the mean of its divisors is an integer number (40590720).

Almost surely, 2^644904366 is an apocalyptic number.

644904366 is an abundant number, since it is smaller than the sum of its proper divisors (653998674).

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

644904366 is a wasteful number, since it uses less digits than its factorization.

644904366 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1600.

The product of its (nonzero) digits is 373248, while the sum is 42.

The square root of 644904366 is about 25394.9673360688. The cubic root of 644904366 is about 863.9695553616.

The spelling of 644904366 in words is "six hundred forty-four million, nine hundred four thousand, three hundred sixty-six".