1991711167729 has 2 divisors, whose sum is σ = 1991711167730. Its totient is φ = 1991711167728.

The previous prime is 1991711167723. The next prime is 1991711167739. The reversal of 1991711167729 is 9277611171991.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1713813502129 + 277897665600 = 1309127^2 + 527160^2 .

It is an emirp because it is prime and its reverse (9277611171991) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1991711167729 - 2⁹ = 1991711167217 is a prime.

It is not a weakly prime, because it can be changed into another prime (1991711167723) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 995855583864 + 995855583865.

It is an arithmetic number, because the mean of its divisors is an integer number (995855583865).

Almost surely, 2^{1991711167729} is an apocalyptic number.

It is an amenable number.

1991711167729 is a deficient number, since it is larger than the sum of its proper divisors (1).

1991711167729 is an equidigital number, since it uses as much as digits as its factorization.

1991711167729 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3000564, while the sum is 61.

The spelling of 1991711167729 in words is "one trillion, nine hundred ninety-one billion, seven hundred eleven million, one hundred sixty-seven thousand, seven hundred twenty-nine".