644685000 has 80 divisors (see below), whose sum is σ = 2014042800. Its totient is φ = 171912000.

The previous prime is 644684981. The next prime is 644685007. The reversal of 644685000 is 586446.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (644685007) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6490 + ... + 36489.

It is an arithmetic number, because the mean of its divisors is an integer number (25175535).

Almost surely, 2^644685000 is an apocalyptic number.

644685000 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644685000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1007021400).

644685000 is an abundant number, since it is smaller than the sum of its proper divisors (1369357800).

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

644685000 is a wasteful number, since it uses less digits than its factorization.

644685000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43008 (or 42989 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 33.

The square root of 644685000 is about 25390.6478846051. The cubic root of 644685000 is about 863.8715837094.

The spelling of 644685000 in words is "six hundred forty-four million, six hundred eighty-five thousand".