644676953388 has 192 divisors, whose sum is σ = 1754938967040. Its totient is φ = 182539348992.

The previous prime is 644676953387. The next prime is 644676953413. The reversal of 644676953388 is 883359676446.

644676953388 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (69).

It is not an unprimeable number, because it can be changed into a prime (644676953387) 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, 29435770 + ... + 29457662.

It is an arithmetic number, because the mean of its divisors is an integer number (9140307120).

Almost surely, 2^644676953388 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 644676953388, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (877469483520).

644676953388 is an abundant number, since it is smaller than the sum of its proper divisors (1110262013652).

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

644676953388 is a wasteful number, since it uses less digits than its factorization.

644676953388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22248 (or 22246 counting only the distinct ones).

The product of its digits is 627056640, while the sum is 69.

The spelling of 644676953388 in words is "six hundred forty-four billion, six hundred seventy-six million, nine hundred fifty-three thousand, three hundred eighty-eight".