6688640 has 64 divisors (see below), whose sum is σ = 18286560. Its totient is φ = 2291712.

The previous prime is 6688639. The next prime is 6688651. The reversal of 6688640 is 468866.

It is a tau number, because it is divible by the number of its divisors (64).

It is a zygodrome in base 2.

It is a junction number, because it is equal to n+sod(n) for n = 6688594 and 6688603.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3734 + ... + 5226.

Almost surely, 2^6688640 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 6688640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (9143280).

6688640 is an abundant number, since it is smaller than the sum of its proper divisors (11597920).

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

6688640 is a wasteful number, since it uses less digits than its factorization.

6688640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1519 (or 1507 counting only the distinct ones).

The product of its (nonzero) digits is 55296, while the sum is 38.

The square root of 6688640 is about 2586.2405147240. The cubic root of 6688640 is about 188.4137559957.

The spelling of 6688640 in words is "six million, six hundred eighty-eight thousand, six hundred forty".