191291221873 has 2 divisors, whose sum is σ = 191291221874. Its totient is φ = 191291221872.

The previous prime is 191291221843. The next prime is 191291221883. The reversal of 191291221873 is 378122192191.

191291221873 is digitally balanced in base 2, 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., 190822196224 + 469025649 = 436832^2 + 21657^2 .

It is an emirp because it is prime and its reverse (378122192191) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191291221873 is a prime.

It is not a weakly prime, because it can be changed into another prime (191291221813) 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, 95645610936 + 95645610937.

It is an arithmetic number, because the mean of its divisors is an integer number (95645610937).

Almost surely, 2^191291221873 is an apocalyptic number.

It is an amenable number.

191291221873 is a deficient number, since it is larger than the sum of its proper divisors (1).

191291221873 is an equidigital number, since it uses as much as digits as its factorization.

191291221873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 108864, while the sum is 46.

The spelling of 191291221873 in words is "one hundred ninety-one billion, two hundred ninety-one million, two hundred twenty-one thousand, eight hundred seventy-three".