191694391321 has 2 divisors, whose sum is σ = 191694391322. Its totient is φ = 191694391320.

The previous prime is 191694391303. The next prime is 191694391363. The reversal of 191694391321 is 123193496191.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 144403800025 + 47290591296 = 380005^2 + 217464^2 .

It is an emirp because it is prime and its reverse (123193496191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 191694391321 - 2²⁹ = 191157520409 is a prime.

It is not a weakly prime, because it can be changed into another prime (191694391381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95847195660 + 95847195661.

It is an arithmetic number, because the mean of its divisors is an integer number (95847195661).

Almost surely, 2^191694391321 is an apocalyptic number.

It is an amenable number.

191694391321 is a deficient number, since it is larger than the sum of its proper divisors (1).

191694391321 is an equidigital number, since it uses as much as digits as its factorization.

191694391321 is an evil number, because the sum of its binary digits is even.

The product of its digits is 314928, while the sum is 49.

The spelling of 191694391321 in words is "one hundred ninety-one billion, six hundred ninety-four million, three hundred ninety-one thousand, three hundred twenty-one".