644336396000 has 192 divisors, whose sum is σ = 1742352970176. Its totient is φ = 232228864000.

The previous prime is 644336395951. The next prime is 644336396003. The reversal of 644336396000 is 693633446.

It is a Harshad number since it is a multiple of its sum of digits (44).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644336396003) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 4907204 + ... + 5036796.

It is an arithmetic number, because the mean of its divisors is an integer number (9074755053).

Almost surely, 2^644336396000 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 644336396000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (871176485088).

644336396000 is an abundant number, since it is smaller than the sum of its proper divisors (1098016574176).

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

644336396000 is a wasteful number, since it uses less digits than its factorization.

644336396000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 129742 (or 129724 counting only the distinct ones).

The product of its (nonzero) digits is 839808, while the sum is 44.

The spelling of 644336396000 in words is "six hundred forty-four billion, three hundred thirty-six million, three hundred ninety-six thousand".