644494032 has 240 divisors, whose sum is σ = 2242356480. Its totient is φ = 168265728.

The previous prime is 644494007. The next prime is 644494043. The reversal of 644494032 is 230494446.

644494032 is a `hidden beast` number, since 644 + 4 + 9 + 4 + 0 + 3 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1795069 + ... + 1795427.

It is an arithmetic number, because the mean of its divisors is an integer number (9343152).

Almost surely, 2^644494032 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644494032, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1121178240).

644494032 is an abundant number, since it is smaller than the sum of its proper divisors (1597862448).

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

644494032 is a wasteful number, since it uses less digits than its factorization.

644494032 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530 (or 521 counting only the distinct ones).

The product of its (nonzero) digits is 82944, while the sum is 36.

The square root of 644494032 is about 25386.8870088477. The cubic root of 644494032 is about 863.7862768693.

The spelling of 644494032 in words is "six hundred forty-four million, four hundred ninety-four thousand, thirty-two".