644624800 has 72 divisors (see below), whose sum is σ = 1585960992. Its totient is φ = 255840000.

The previous prime is 644624777. The next prime is 644624807. The reversal of 644624800 is 8426446.

It is a happy number.

It is a super-2 number, since 2×644624800² = 831082265550080000, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (644624807) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 101725 + ... + 107875.

It is an arithmetic number, because the mean of its divisors is an integer number (22027236).

Almost surely, 2^644624800 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 644624800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (792980496).

644624800 is an abundant number, since it is smaller than the sum of its proper divisors (941336192).

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

644624800 is a wasteful number, since it uses less digits than its factorization.

644624800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6302 (or 6289 counting only the distinct ones).

The product of its (nonzero) digits is 36864, while the sum is 34.

The square root of 644624800 is about 25389.4623810746. The cubic root of 644624800 is about 863.8446937356.

The spelling of 644624800 in words is "six hundred forty-four million, six hundred twenty-four thousand, eight hundred".