644140800 has 324 divisors, whose sum is σ = 2357520984. Its totient is φ = 167731200.

The previous prime is 644140771. The next prime is 644140801. The reversal of 644140800 is 8041446.

644140800 is a `hidden beast` number, since 644 + 14 + 0 + 8 + 0 + 0 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644140801) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 3052695 + ... + 3052905.

Almost surely, 2^644140800 is an apocalyptic number.

644140800 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 644140800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1178760492).

644140800 is an abundant number, since it is smaller than the sum of its proper divisors (1713380184).

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

644140800 is a wasteful number, since it uses less digits than its factorization.

644140800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 296 (or 274 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 27.

The square root of 644140800 is about 25379.9290779151. The cubic root of 644140800 is about 863.6284410589.

The spelling of 644140800 in words is "six hundred forty-four million, one hundred forty thousand, eight hundred".