644372904 has 64 divisors (see below), whose sum is σ = 1852439040. Its totient is φ = 182969280.

The previous prime is 644372873. The next prime is 644372909. The reversal of 644372904 is 409273446.

It is not an unprimeable number, because it can be changed into a prime (644372909) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 15619 + ... + 39149.

It is an arithmetic number, because the mean of its divisors is an integer number (28944360).

Almost surely, 2^644372904 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 644372904, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (926219520).

644372904 is an abundant number, since it is smaller than the sum of its proper divisors (1208066136).

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

644372904 is a wasteful number, since it uses less digits than its factorization.

644372904 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23710 (or 23706 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 39.

The square root of 644372904 is about 25384.5012556875. The cubic root of 644372904 is about 863.7321593475.

It can be divided in two parts, 6 and 44372904, that added together give a triangular number (44372910 = T₉₄₂₀).

The spelling of 644372904 in words is "six hundred forty-four million, three hundred seventy-two thousand, nine hundred four".