644775597 has 24 divisors (see below), whose sum is σ = 941460000. Its totient is φ = 425206368.

The previous prime is 644775557. The next prime is 644775601. The reversal of 644775597 is 795577446.

644775597 is a `hidden beast` number, since 6 + 4 + 47 + 7 + 5 + 597 = 666.

It is not a de Polignac number, because 644775597 - 2¹⁸ = 644513453 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644775517) by changing a digit.

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 23 ways as a sum of consecutive naturals, for example, 378654 + ... + 380352.

It is an arithmetic number, because the mean of its divisors is an integer number (39227500).

Almost surely, 2^644775597 is an apocalyptic number.

It is an amenable number.

644775597 is a deficient number, since it is larger than the sum of its proper divisors (296684403).

644775597 is a wasteful number, since it uses less digits than its factorization.

644775597 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2137 (or 2134 counting only the distinct ones).

The product of its digits is 7408800, while the sum is 54.

The square root of 644775597 is about 25392.4318843233. The cubic root of 644775597 is about 863.9120481781.

The spelling of 644775597 in words is "six hundred forty-four million, seven hundred seventy-five thousand, five hundred ninety-seven".