644323104320 has 448 divisors, whose sum is σ = 1865551564800. Its totient is φ = 207277056000.

The previous prime is 644323104311. The next prime is 644323104329. The reversal of 644323104320 is 23401323446.

It is an interprime number because it is at equal distance from previous prime (644323104311) and next prime (644323104329).

It is a tau number, because it is divible by the number of its divisors (448).

It is a Harshad number since it is a multiple of its sum of digits (32).

It is not an unprimeable number, because it can be changed into a prime (644323104329) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 701112821 + ... + 701113739.

It is an arithmetic number, because the mean of its divisors is an integer number (4164177600).

Almost surely, 2^644323104320 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 644323104320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (932775782400).

644323104320 is an abundant number, since it is smaller than the sum of its proper divisors (1221228460480).

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

644323104320 is a wasteful number, since it uses less digits than its factorization.

644323104320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1266 (or 1256 counting only the distinct ones).

The product of its (nonzero) digits is 41472, while the sum is 32.

Adding to 644323104320 its reverse (23401323446), we get a palindrome (667724427766).

The spelling of 644323104320 in words is "six hundred forty-four billion, three hundred twenty-three million, one hundred four thousand, three hundred twenty".