644491574 has 16 divisors (see below), whose sum is σ = 984579840. Its totient is φ = 316314600.

The previous prime is 644491553. The next prime is 644491583. The reversal of 644491574 is 475194446.

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, 83999 + ... + 91349.

It is an arithmetic number, because the mean of its divisors is an integer number (61536240).

Almost surely, 2^644491574 is an apocalyptic number.

644491574 is a deficient number, since it is larger than the sum of its proper divisors (340088266).

644491574 is a wasteful number, since it uses less digits than its factorization.

644491574 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8155.

The product of its digits is 483840, while the sum is 44.

The square root of 644491574 is about 25386.8385979822. The cubic root of 644491574 is about 863.7851787524.

The spelling of 644491574 in words is "six hundred forty-four million, four hundred ninety-one thousand, five hundred seventy-four".