644097972 has 96 divisors (see below), whose sum is σ = 1827560448. Its totient is φ = 172353024.

The previous prime is 644097931. The next prime is 644097983. The reversal of 644097972 is 279790446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 323163 + ... + 325149.

It is an arithmetic number, because the mean of its divisors is an integer number (19037088).

Almost surely, 2^644097972 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 644097972, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (913780224).

644097972 is an abundant number, since it is smaller than the sum of its proper divisors (1183462476).

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

644097972 is a wasteful number, since it uses less digits than its factorization.

644097972 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2245 (or 2243 counting only the distinct ones).

The product of its (nonzero) digits is 762048, while the sum is 48.

The square root of 644097972 is about 25379.0853263076. The cubic root of 644097972 is about 863.6093001616.

The spelling of 644097972 in words is "six hundred forty-four million, ninety-seven thousand, nine hundred seventy-two".