6668908691 has 2 divisors, whose sum is σ = 6668908692. Its totient is φ = 6668908690.

The previous prime is 6668908663. The next prime is 6668908721. The reversal of 6668908691 is 1968098666.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6668908691 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 6668908691.

It is not a weakly prime, because it can be changed into another prime (6668908091) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3334454345 + 3334454346.

It is an arithmetic number, because the mean of its divisors is an integer number (3334454346).

Almost surely, 2^6668908691 is an apocalyptic number.

6668908691 is a deficient number, since it is larger than the sum of its proper divisors (1).

6668908691 is an equidigital number, since it uses as much as digits as its factorization.

6668908691 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6718464, while the sum is 59.

The square root of 6668908691 is about 81663.3864776621. The cubic root of 6668908691 is about 1882.2830166826.

The spelling of 6668908691 in words is "six billion, six hundred sixty-eight million, nine hundred eight thousand, six hundred ninety-one".