644927772 has 12 divisors (see below), whose sum is σ = 1504831496. Its totient is φ = 214975920.

The previous prime is 644927753. The next prime is 644927779. The reversal of 644927772 is 277729446.

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644927779) 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 3 ways as a sum of consecutive naturals, for example, 26871979 + ... + 26872002.

Almost surely, 2^644927772 is an apocalyptic number.

It is an amenable number.

644927772 is an abundant number, since it is smaller than the sum of its proper divisors (859903724).

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

644927772 is a wasteful number, since it uses less digits than its factorization.

644927772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53743988 (or 53743986 counting only the distinct ones).

The product of its digits is 1185408, while the sum is 48.

The square root of 644927772 is about 25395.4281712280. The cubic root of 644927772 is about 863.9800074678.

The spelling of 644927772 in words is "six hundred forty-four million, nine hundred twenty-seven thousand, seven hundred seventy-two".