191317661 has 2 divisors, whose sum is σ = 191317662. Its totient is φ = 191317660.

The previous prime is 191317613. The next prime is 191317667. The reversal of 191317661 is 166713191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 96157636 + 95160025 = 9806^2 + 9755^2 .

It is a cyclic number.

It is not a de Polignac number, because 191317661 - 2¹⁰ = 191316637 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191317667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95658830 + 95658831.

It is an arithmetic number, because the mean of its divisors is an integer number (95658831).

Almost surely, 2^191317661 is an apocalyptic number.

It is an amenable number.

191317661 is a deficient number, since it is larger than the sum of its proper divisors (1).

191317661 is an equidigital number, since it uses as much as digits as its factorization.

191317661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6804, while the sum is 35.

The square root of 191317661 is about 13831.7627582315. The cubic root of 191317661 is about 576.2156119970.

The spelling of 191317661 in words is "one hundred ninety-one million, three hundred seventeen thousand, six hundred sixty-one".