644346375078 has 192 divisors, whose sum is σ = 1658391072768. Its totient is φ = 165806403840.

The previous prime is 644346375061. The next prime is 644346375139. The reversal of 644346375078 is 870573643446.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 7714476 + ... + 7797552.

It is an arithmetic number, because the mean of its divisors is an integer number (8637453504).

Almost surely, 2^644346375078 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644346375078, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (829195536384).

644346375078 is an abundant number, since it is smaller than the sum of its proper divisors (1014044697690).

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

644346375078 is a wasteful number, since it uses less digits than its factorization.

644346375078 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 83187 (or 83180 counting only the distinct ones).

The product of its (nonzero) digits is 40642560, while the sum is 57.

The spelling of 644346375078 in words is "six hundred forty-four billion, three hundred forty-six million, three hundred seventy-five thousand, seventy-eight".