644355212264 has 8 divisors (see below), whose sum is σ = 1208166023010. Its totient is φ = 322177606128.

The previous prime is 644355212233. The next prime is 644355212297. The reversal of 644355212264 is 462212553446.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 534755812900 + 109599399364 = 731270^2 + 331058^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40272200759 + ... + 40272200774.

Almost surely, 2^644355212264 is an apocalyptic number.

It is an amenable number.

644355212264 is a deficient number, since it is larger than the sum of its proper divisors (563810810746).

644355212264 is a wasteful number, since it uses less digits than its factorization.

644355212264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 80544401539 (or 80544401535 counting only the distinct ones).

The product of its digits is 1382400, while the sum is 44.

The spelling of 644355212264 in words is "six hundred forty-four billion, three hundred fifty-five million, two hundred twelve thousand, two hundred sixty-four".