17991434081 has 2 divisors, whose sum is σ = 17991434082. Its totient is φ = 17991434080.

The previous prime is 17991434057. The next prime is 17991434093. The reversal of 17991434081 is 18043419971.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12901325056 + 5090109025 = 113584^2 + 71345^2 .

It is a cyclic number.

It is not a de Polignac number, because 17991434081 - 2¹⁸ = 17991171937 is a prime.

It is a super-2 number, since 2×17991434081² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (17990434081) 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, 8995717040 + 8995717041.

It is an arithmetic number, because the mean of its divisors is an integer number (8995717041).

Almost surely, 2^17991434081 is an apocalyptic number.

It is an amenable number.

17991434081 is a deficient number, since it is larger than the sum of its proper divisors (1).

17991434081 is an equidigital number, since it uses as much as digits as its factorization.

17991434081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 217728, while the sum is 47.

The spelling of 17991434081 in words is "seventeen billion, nine hundred ninety-one million, four hundred thirty-four thousand, eighty-one".