644598860 has 48 divisors (see below), whose sum is σ = 1437549120. Its totient is φ = 241950720.

The previous prime is 644598839. The next prime is 644598907. The reversal of 644598860 is 68895446.

It is a happy number.

644598860 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (50) coincides with the sum of the digits of its prime factors.

It is a junction number, because it is equal to n+sod(n) for n = 644598799 and 644598808.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 119420 + ... + 124700.

It is an arithmetic number, because the mean of its divisors is an integer number (29948940).

Almost surely, 2^644598860 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 644598860, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (718774560).

644598860 is an abundant number, since it is smaller than the sum of its proper divisors (792950260).

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

644598860 is a wasteful number, since it uses less digits than its factorization.

644598860 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5666 (or 5664 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 50.

The square root of 644598860 is about 25388.9515340827. The cubic root of 644598860 is about 863.8331064102.

The spelling of 644598860 in words is "six hundred forty-four million, five hundred ninety-eight thousand, eight hundred sixty".