644844320080128 has 432 divisors, whose sum is σ = 2165405138297856. Its totient is φ = 180726409543680.

The previous prime is 644844320080127. The next prime is 644844320080189. The reversal of 644844320080128 is 821080023448446.

It is a happy number.

644844320080128 is a `hidden beast` number, since 6 + 4 + 4 + 8 + 4 + 432 + 0 + 0 + 80 + 128 = 666.

It is not an unprimeable number, because it can be changed into a prime (644844320080127) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 4129383426 + ... + 4129539582.

It is an arithmetic number, because the mean of its divisors is an integer number (5012511894208).

Almost surely, 2^{644844320080128} 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 644844320080128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1082702569148928).

644844320080128 is an abundant number, since it is smaller than the sum of its proper divisors (1520560818217728).

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

644844320080128 is a wasteful number, since it uses less digits than its factorization.

644844320080128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 161070 (or 161053 counting only the distinct ones).

The product of its (nonzero) digits is 9437184, while the sum is 54.

The spelling of 644844320080128 in words is "six hundred forty-four trillion, eight hundred forty-four billion, three hundred twenty million, eighty thousand, one hundred twenty-eight".