644792389632 has 624 divisors, whose sum is σ = 2086589756160. Its totient is φ = 198195019776.

The previous prime is 644792389627. The next prime is 644792389669. The reversal of 644792389632 is 236983297446.

644792389632 is a `hidden beast` number, since 6 + 4 + 479 + 23 + 89 + 63 + 2 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 644792389632.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 896790169 + ... + 896790887.

It is an arithmetic number, because the mean of its divisors is an integer number (3343893840).

Almost surely, 2^644792389632 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 644792389632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1043294878080).

644792389632 is an abundant number, since it is smaller than the sum of its proper divisors (1441797366528).

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

644792389632 is an equidigital number, since it uses as much as digits as its factorization.

644792389632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 828 (or 794 counting only the distinct ones).

The product of its digits is 94058496, while the sum is 63.

The spelling of 644792389632 in words is "six hundred forty-four billion, seven hundred ninety-two million, three hundred eighty-nine thousand, six hundred thirty-two".