191316661 has 2 divisors, whose sum is σ = 191316662. Its totient is φ = 191316660.

The previous prime is 191316647. The next prime is 191316667. The reversal of 191316661 is 166613191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 187964100 + 3352561 = 13710^2 + 1831^2 .

It is a cyclic number.

It is not a de Polignac number, because 191316661 - 2²⁵ = 157762229 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191316667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95658330 + 95658331.

It is an arithmetic number, because the mean of its divisors is an integer number (95658331).

Almost surely, 2^191316661 is an apocalyptic number.

It is an amenable number.

191316661 is a deficient number, since it is larger than the sum of its proper divisors (1).

191316661 is an equidigital number, since it uses as much as digits as its factorization.

191316661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5832, while the sum is 34.

The square root of 191316661 is about 13831.7266095018. The cubic root of 191316661 is about 576.2146080531.

The spelling of 191316661 in words is "one hundred ninety-one million, three hundred sixteen thousand, six hundred sixty-one".