644450400 has 432 divisors, whose sum is σ = 2534837760. Its totient is φ = 152755200.

The previous prime is 644450369. The next prime is 644450419. The reversal of 644450400 is 4054446.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 6256749 + ... + 6256851.

It is an arithmetic number, because the mean of its divisors is an integer number (5867680).

Almost surely, 2^644450400 is an apocalyptic number.

644450400 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 644450400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1267418880).

644450400 is an abundant number, since it is smaller than the sum of its proper divisors (1890387360).

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

644450400 is a wasteful number, since it uses less digits than its factorization.

644450400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219 (or 203 counting only the distinct ones).

The product of its (nonzero) digits is 7680, while the sum is 27.

The square root of 644450400 is about 25386.0276530220. The cubic root of 644450400 is about 863.7667837623.

The spelling of 644450400 in words is "six hundred forty-four million, four hundred fifty thousand, four hundred".