644448816000 has 768 divisors, whose sum is σ = 2533406803200. Its totient is φ = 155696640000.

The previous prime is 644448815993. The next prime is 644448816023. The reversal of 644448816000 is 618844446.

644448816000 is a `hidden beast` number, since 6 + 4 + 4 + 4 + 488 + 160 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 663695515 + ... + 663696485.

It is an arithmetic number, because the mean of its divisors is an integer number (3298706775).

Almost surely, 2^644448816000 is an apocalyptic number.

644448816000 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 644448816000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1266703401600).

644448816000 is an abundant number, since it is smaller than the sum of its proper divisors (1888957987200).

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

644448816000 is a wasteful number, since it uses less digits than its factorization.

644448816000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1436 (or 1411 counting only the distinct ones).

The product of its (nonzero) digits is 589824, while the sum is 45.

The spelling of 644448816000 in words is "six hundred forty-four billion, four hundred forty-eight million, eight hundred sixteen thousand".