6691555817 has 2 divisors, whose sum is σ = 6691555818. Its totient is φ = 6691555816.

The previous prime is 6691555751. The next prime is 6691555841. The reversal of 6691555817 is 7185551966.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6590030041 + 101525776 = 81179^2 + 10076^2 .

It is a cyclic number.

It is not a de Polignac number, because 6691555817 - 2¹² = 6691551721 is a prime.

It is not a weakly prime, because it can be changed into another prime (6691555847) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3345777908 + 3345777909.

It is an arithmetic number, because the mean of its divisors is an integer number (3345777909).

Almost surely, 2^6691555817 is an apocalyptic number.

It is an amenable number.

6691555817 is a deficient number, since it is larger than the sum of its proper divisors (1).

6691555817 is an equidigital number, since it uses as much as digits as its factorization.

6691555817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2268000, while the sum is 53.

The square root of 6691555817 is about 81801.9303989826. The cubic root of 6691555817 is about 1884.4113077946.

The spelling of 6691555817 in words is "six billion, six hundred ninety-one million, five hundred fifty-five thousand, eight hundred seventeen".