6691000891 has 2 divisors, whose sum is σ = 6691000892. Its totient is φ = 6691000890.

The previous prime is 6691000873. The next prime is 6691000903. The reversal of 6691000891 is 1980001966.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 6691000891 - 2⁷ = 6691000763 is a prime.

It is not a weakly prime, because it can be changed into another prime (6691000831) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3345500445 + 3345500446.

It is an arithmetic number, because the mean of its divisors is an integer number (3345500446).

Almost surely, 2^6691000891 is an apocalyptic number.

6691000891 is a deficient number, since it is larger than the sum of its proper divisors (1).

6691000891 is an equidigital number, since it uses as much as digits as its factorization.

6691000891 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23328, while the sum is 40.

The square root of 6691000891 is about 81798.5384404880. The cubic root of 6691000891 is about 1884.3592153881.

The spelling of 6691000891 in words is "six billion, six hundred ninety-one million, eight hundred ninety-one", and thus it is an aban number.