6647645872 has 80 divisors (see below), whose sum is σ = 15261076800. Its totient is φ = 2744663040.

The previous prime is 6647645867. The next prime is 6647645891. The reversal of 6647645872 is 2785467466.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1651222 + ... + 1655242.

It is an arithmetic number, because the mean of its divisors is an integer number (190763460).

Almost surely, 2^6647645872 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 6647645872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7630538400).

6647645872 is an abundant number, since it is smaller than the sum of its proper divisors (8613430928).

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

6647645872 is a wasteful number, since it uses less digits than its factorization.

6647645872 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4574 (or 4568 counting only the distinct ones).

The product of its digits is 13547520, while the sum is 55.

The square root of 6647645872 is about 81533.0967889728. The cubic root of 6647645872 is about 1880.2804274607.

The spelling of 6647645872 in words is "six billion, six hundred forty-seven million, six hundred forty-five thousand, eight hundred seventy-two".