644991675 has 24 divisors (see below), whose sum is σ = 1069247040. Its totient is φ = 343072800.

The previous prime is 644991661. The next prime is 644991707. The reversal of 644991675 is 576199446.

It is not a de Polignac number, because 644991675 - 2⁸ = 644991419 is a prime.

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 23 ways as a sum of consecutive naturals, for example, 17080 + ... + 39770.

It is an arithmetic number, because the mean of its divisors is an integer number (44551960).

Almost surely, 2^644991675 is an apocalyptic number.

644991675 is a deficient number, since it is larger than the sum of its proper divisors (424255365).

644991675 is a wasteful number, since it uses less digits than its factorization.

644991675 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23083 (or 23078 counting only the distinct ones).

The product of its digits is 1632960, while the sum is 51.

The square root of 644991675 is about 25396.6862995943. The cubic root of 644991675 is about 864.0085424931.

The spelling of 644991675 in words is "six hundred forty-four million, nine hundred ninety-one thousand, six hundred seventy-five".