644131056400 has 240 divisors, whose sum is σ = 1709114359680. Its totient is φ = 231836774400.

The previous prime is 644131056379. The next prime is 644131056419. The reversal of 644131056400 is 4650131446.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 32848999 + ... + 32868601.

It is an arithmetic number, because the mean of its divisors is an integer number (7121309832).

Almost surely, 2^644131056400 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 644131056400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (854557179840).

644131056400 is an abundant number, since it is smaller than the sum of its proper divisors (1064983303280).

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

644131056400 is a wasteful number, since it uses less digits than its factorization.

644131056400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19794 (or 19783 counting only the distinct ones).

The product of its (nonzero) digits is 34560, while the sum is 34.

Adding to 644131056400 its reverse (4650131446), we get a palindrome (648781187846).

The spelling of 644131056400 in words is "six hundred forty-four billion, one hundred thirty-one million, fifty-six thousand, four hundred".