644265853 has 8 divisors (see below), whose sum is σ = 803240640. Its totient is φ = 502025280.

The previous prime is 644265833. The next prime is 644265863. The reversal of 644265853 is 358562446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 644265853 - 2⁵ = 644265821 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644265823) 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 7 ways as a sum of consecutive naturals, for example, 4183468 + ... + 4183621.

It is an arithmetic number, because the mean of its divisors is an integer number (100405080).

Almost surely, 2^644265853 is an apocalyptic number.

It is an amenable number.

644265853 is a deficient number, since it is larger than the sum of its proper divisors (158974787).

644265853 is a wasteful number, since it uses less digits than its factorization.

644265853 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8367107.

The product of its digits is 691200, while the sum is 43.

The square root of 644265853 is about 25382.3925783209. The cubic root of 644265853 is about 863.6843254966.

The spelling of 644265853 in words is "six hundred forty-four million, two hundred sixty-five thousand, eight hundred fifty-three".