644270872320 has 576 divisors, whose sum is σ = 2417499302400. Its totient is φ = 162026127360.

The previous prime is 644270872313. The next prime is 644270872327. The reversal of 644270872320 is 23278072446.

It is an interprime number because it is at equal distance from previous prime (644270872313) and next prime (644270872327).

It is a tau number, because it is divible by the number of its divisors (576).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644270872327) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 152995015 + ... + 152999225.

It is an arithmetic number, because the mean of its divisors is an integer number (4197047400).

Almost surely, 2^644270872320 is an apocalyptic number.

644270872320 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 644270872320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1208749651200).

644270872320 is an abundant number, since it is smaller than the sum of its proper divisors (1773228430080).

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

644270872320 is a wasteful number, since it uses less digits than its factorization.

644270872320 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4493 (or 4473 counting only the distinct ones).

The product of its (nonzero) digits is 903168, while the sum is 45.

The spelling of 644270872320 in words is "six hundred forty-four billion, two hundred seventy million, eight hundred seventy-two thousand, three hundred twenty".