644944076 has 36 divisors (see below), whose sum is σ = 1326496248. Its totient is φ = 273547008.

The previous prime is 644944039. The next prime is 644944093. The reversal of 644944076 is 670449446.

It is a super-2 number, since 2×644944076² = 831905722334987552, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2051 + ... + 35973.

It is an arithmetic number, because the mean of its divisors is an integer number (36847118).

Almost surely, 2^644944076 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 644944076, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (663248124).

644944076 is an abundant number, since it is smaller than the sum of its proper divisors (681552172).

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

644944076 is a wasteful number, since it uses less digits than its factorization.

644944076 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34038 (or 34029 counting only the distinct ones).

The product of its (nonzero) digits is 580608, while the sum is 44.

The square root of 644944076 is about 25395.7491718595. The cubic root of 644944076 is about 863.9872879788.

The spelling of 644944076 in words is "six hundred forty-four million, nine hundred forty-four thousand, seventy-six".