644491000 has 32 divisors (see below), whose sum is σ = 1508111280. Its totient is φ = 257796000.

The previous prime is 644490997. The next prime is 644491021. The reversal of 644491000 is 194446.

644491000 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a self number, because there is not a number n which added to its sum of digits gives 644491000.

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, 321246 + ... + 323245.

Almost surely, 2^644491000 is an apocalyptic number.

It is an amenable number.

644491000 is an abundant number, since it is smaller than the sum of its proper divisors (863620280).

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

644491000 is a wasteful number, since it uses less digits than its factorization.

644491000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 644512 (or 644498 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 644491000 is about 25386.8272929092. The cubic root of 644491000 is about 863.7849223162.

The spelling of 644491000 in words is "six hundred forty-four million, four hundred ninety-one thousand".