644975189 has 16 divisors (see below), whose sum is σ = 703213632. Its totient is φ = 589171968.

The previous prime is 644975183. The next prime is 644975203. The reversal of 644975189 is 981579446.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644975189 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644975189.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644975183) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 116447 + ... + 121859.

It is an arithmetic number, because the mean of its divisors is an integer number (43950852).

Almost surely, 2^644975189 is an apocalyptic number.

It is an amenable number.

644975189 is a deficient number, since it is larger than the sum of its proper divisors (58238443).

644975189 is a wasteful number, since it uses less digits than its factorization.

644975189 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5636.

The product of its digits is 2177280, while the sum is 53.

The square root of 644975189 is about 25396.3617276176. The cubic root of 644975189 is about 864.0011810719.

The spelling of 644975189 in words is "six hundred forty-four million, nine hundred seventy-five thousand, one hundred eighty-nine".