6688306661 has 2 divisors, whose sum is σ = 6688306662. Its totient is φ = 6688306660.

The previous prime is 6688306621. The next prime is 6688306693. The reversal of 6688306661 is 1666038866.

6688306661 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6207864100 + 480442561 = 78790^2 + 21919^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6688306661 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6688306621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3344153330 + 3344153331.

It is an arithmetic number, because the mean of its divisors is an integer number (3344153331).

Almost surely, 2^6688306661 is an apocalyptic number.

It is an amenable number.

6688306661 is a deficient number, since it is larger than the sum of its proper divisors (1).

6688306661 is an equidigital number, since it uses as much as digits as its factorization.

6688306661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1492992, while the sum is 50.

The square root of 6688306661 is about 81782.0680895268. The cubic root of 6688306661 is about 1884.1062597744.

The spelling of 6688306661 in words is "six billion, six hundred eighty-eight million, three hundred six thousand, six hundred sixty-one".