191497249661 has 2 divisors, whose sum is σ = 191497249662. Its totient is φ = 191497249660.

The previous prime is 191497249549. The next prime is 191497249703. The reversal of 191497249661 is 166942794191.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152951388100 + 38545861561 = 391090^2 + 196331^2 .

It is an emirp because it is prime and its reverse (166942794191) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 191497249661 - 2²² = 191493055357 is a prime.

It is a super-2 number, since 2×191497249661² (a number of 23 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 191497249661.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (191497249861) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 95748624830 + 95748624831.

It is an arithmetic number, because the mean of its divisors is an integer number (95748624831).

Almost surely, 2^191497249661 is an apocalyptic number.

It is an amenable number.

191497249661 is a deficient number, since it is larger than the sum of its proper divisors (1).

191497249661 is an equidigital number, since it uses as much as digits as its factorization.

191497249661 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5878656, while the sum is 59.

The spelling of 191497249661 in words is "one hundred ninety-one billion, four hundred ninety-seven million, two hundred forty-nine thousand, six hundred sixty-one".