644661212 has 48 divisors (see below), whose sum is σ = 1274501760. Its totient is φ = 283295232.

The previous prime is 644661191. The next prime is 644661223. The reversal of 644661212 is 212166446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 86864 + ... + 93992.

It is an arithmetic number, because the mean of its divisors is an integer number (26552120).

Almost surely, 2^644661212 is an apocalyptic number.

It is an amenable number.

644661212 is a deficient number, since it is larger than the sum of its proper divisors (629840548).

644661212 is a wasteful number, since it uses less digits than its factorization.

644661212 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7230 (or 7228 counting only the distinct ones).

The product of its digits is 13824, while the sum is 32.

The square root of 644661212 is about 25390.1794400906. The cubic root of 644661212 is about 863.8609583497.

The spelling of 644661212 in words is "six hundred forty-four million, six hundred sixty-one thousand, two hundred twelve".