644342688 has 264 divisors, whose sum is σ = 2142758016. Its totient is φ = 188956800.

The previous prime is 644342683. The next prime is 644342711. The reversal of 644342688 is 886243446.

644342688 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (264).

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 (644342683) by changing a digit.

It is a polite number, since it can be written in 43 ways as a sum of consecutive naturals, for example, 20785233 + ... + 20785263.

Almost surely, 2^644342688 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 644342688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1071379008).

644342688 is an abundant number, since it is smaller than the sum of its proper divisors (1498415328).

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

644342688 is an equidigital number, since it uses as much as digits as its factorization.

644342688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82 (or 47 counting only the distinct ones).

The product of its digits is 884736, while the sum is 45.

The square root of 644342688 is about 25383.9060823980. The cubic root of 644342688 is about 863.7186583976.

The spelling of 644342688 in words is "six hundred forty-four million, three hundred forty-two thousand, six hundred eighty-eight".