644964188 has 12 divisors (see below), whose sum is σ = 1231295352. Its totient is φ = 293165520.

The previous prime is 644964169. The next prime is 644964191. The reversal of 644964188 is 881469446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7329095 + ... + 7329182.

It is an arithmetic number, because the mean of its divisors is an integer number (102607946).

Almost surely, 2^644964188 is an apocalyptic number.

It is an amenable number.

644964188 is a deficient number, since it is larger than the sum of its proper divisors (586331164).

644964188 is a wasteful number, since it uses less digits than its factorization.

644964188 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14658292 (or 14658290 counting only the distinct ones).

The product of its digits is 1327104, while the sum is 50.

The square root of 644964188 is about 25396.1451405523. The cubic root of 644964188 is about 863.9962687739.

The spelling of 644964188 in words is "six hundred forty-four million, nine hundred sixty-four thousand, one hundred eighty-eight".