644536885 has 8 divisors (see below), whose sum is σ = 775675296. Its totient is φ = 514142160.

The previous prime is 644536883. The next prime is 644536891. The reversal of 644536885 is 588635446.

It is a happy number.

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

It is not a de Polignac number, because 644536885 - 2¹ = 644536883 is a prime.

It is a super-2 number, since 2×644536885² = 830855592251006450, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644536883) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 184011 + ... + 187480.

It is an arithmetic number, because the mean of its divisors is an integer number (96959412).

Almost surely, 2^644536885 is an apocalyptic number.

It is an amenable number.

644536885 is a deficient number, since it is larger than the sum of its proper divisors (131138411).

644536885 is a wasteful number, since it uses less digits than its factorization.

644536885 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 371843.

The product of its digits is 2764800, while the sum is 49.

The square root of 644536885 is about 25387.7309935331. The cubic root of 644536885 is about 863.8054210926.

The spelling of 644536885 in words is "six hundred forty-four million, five hundred thirty-six thousand, eight hundred eighty-five".