644639112 has 48 divisors (see below), whose sum is σ = 1880200140. Its totient is φ = 198350208.

The previous prime is 644639111. The next prime is 644639119. The reversal of 644639112 is 211936446.

644639112 is a `hidden beast` number, since 6 + 4 + 4 + 639 + 1 + 12 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 643839876 + 799236 = 25374^2 + 894^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (644639111) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 343423 + ... + 345294.

Almost surely, 2^644639112 is an apocalyptic number.

It is an amenable number.

644639112 is an abundant number, since it is smaller than the sum of its proper divisors (1235561028).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644639112 is a wasteful number, since it uses less digits than its factorization.

644639112 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 688742 (or 688735 counting only the distinct ones).

The product of its digits is 31104, while the sum is 36.

The square root of 644639112 is about 25389.7442287235. The cubic root of 644639112 is about 863.8510867329.

The spelling of 644639112 in words is "six hundred forty-four million, six hundred thirty-nine thousand, one hundred twelve".