9991731697 has 2 divisors, whose sum is σ = 9991731698. Its totient is φ = 9991731696.

The previous prime is 9991731683. The next prime is 9991731703. The reversal of 9991731697 is 7961371999.

It is a happy number.

9991731697 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., 6921574416 + 3070157281 = 83196^2 + 55409^2 .

It is a cyclic number.

It is not a de Polignac number, because 9991731697 - 2¹⁹ = 9991207409 is a prime.

It is not a weakly prime, because it can be changed into another prime (9991732697) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4995865848 + 4995865849.

It is an arithmetic number, because the mean of its divisors is an integer number (4995865849).

Almost surely, 2^9991731697 is an apocalyptic number.

It is an amenable number.

9991731697 is a deficient number, since it is larger than the sum of its proper divisors (1).

9991731697 is an equidigital number, since it uses as much as digits as its factorization.

9991731697 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5786802, while the sum is 61.

The square root of 9991731697 is about 99958.6499358610. The cubic root of 9991731697 is about 2153.8407423434.

The spelling of 9991731697 in words is "nine billion, nine hundred ninety-one million, seven hundred thirty-one thousand, six hundred ninety-seven".