191497661 has 2 divisors, whose sum is σ = 191497662. Its totient is φ = 191497660.

The previous prime is 191497627. The next prime is 191497667. The reversal of 191497661 is 166794191.

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., 190964761 + 532900 = 13819^2 + 730^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191497661 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 (191497667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95748830 + 95748831.

It is an arithmetic number, because the mean of its divisors is an integer number (95748831).

Almost surely, 2^191497661 is an apocalyptic number.

It is an amenable number.

191497661 is a deficient number, since it is larger than the sum of its proper divisors (1).

191497661 is an equidigital number, since it uses as much as digits as its factorization.

191497661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 44.

The square root of 191497661 is about 13838.2679913348. The cubic root of 191497661 is about 576.3962649468.

The spelling of 191497661 in words is "one hundred ninety-one million, four hundred ninety-seven thousand, six hundred sixty-one".