644527044 has 120 divisors (see below), whose sum is σ = 2027108160. Its totient is φ = 174446784.

The previous prime is 644527031. The next prime is 644527097. The reversal of 644527044 is 440725446.

644527044 is a `hidden beast` number, since 644 + 5 + 2 + 7 + 0 + 4 + 4 = 666.

644527044 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×644527044² = 830830220894755872, which contains 22 as substring.

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

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 35614 + ... + 50570.

It is an arithmetic number, because the mean of its divisors is an integer number (16892568).

Almost surely, 2^644527044 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644527044, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1013554080).

644527044 is an abundant number, since it is smaller than the sum of its proper divisors (1382581116).

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

644527044 is a wasteful number, since it uses less digits than its factorization.

644527044 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14999 (or 14988 counting only the distinct ones).

The product of its (nonzero) digits is 107520, while the sum is 36.

The square root of 644527044 is about 25387.5371787025. The cubic root of 644527044 is about 863.8010247823.

It can be divided in two parts, 6445 and 27044, that added together give a square (33489 = 183²).

The spelling of 644527044 in words is "six hundred forty-four million, five hundred twenty-seven thousand, forty-four".