644266772 has 6 divisors (see below), whose sum is σ = 1127466858. Its totient is φ = 322133384.

The previous prime is 644266759. The next prime is 644266787. The reversal of 644266772 is 277662446.

644266772 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 588256516 + 56010256 = 24254^2 + 7484^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 80533343 + ... + 80533350.

It is an arithmetic number, because the mean of its divisors is an integer number (187911143).

Almost surely, 2^644266772 is an apocalyptic number.

It is an amenable number.

644266772 is a deficient number, since it is larger than the sum of its proper divisors (483200086).

644266772 is a wasteful number, since it uses less digits than its factorization.

644266772 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161066697 (or 161066695 counting only the distinct ones).

The product of its digits is 677376, while the sum is 44.

The square root of 644266772 is about 25382.4106814148. The cubic root of 644266772 is about 863.6847361580.

The spelling of 644266772 in words is "six hundred forty-four million, two hundred sixty-six thousand, seven hundred seventy-two".