6640928 has 48 divisors (see below), whose sum is σ = 15603840. Its totient is φ = 2720256.

The previous prime is 6640927. The next prime is 6640939. The reversal of 6640928 is 8290466.

It is a Cunningham number, because it is equal to 2577²-1.

It is a nialpdrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6640927) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4508 + ... + 5796.

It is an arithmetic number, because the mean of its divisors is an integer number (325080).

Almost surely, 2^6640928 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 6640928, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (7801920).

6640928 is an abundant number, since it is smaller than the sum of its proper divisors (8962912).

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

6640928 is a wasteful number, since it uses less digits than its factorization.

6640928 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1329 (or 1321 counting only the distinct ones).

The product of its (nonzero) digits is 20736, while the sum is 35.

The square root of 6640928 is about 2576.9998059759. Note that the first 3 decimals coincide. The cubic root of 6640928 is about 187.9646832709.

The spelling of 6640928 in words is "six million, six hundred forty thousand, nine hundred twenty-eight".