191691161 has 4 divisors (see below), whose sum is σ = 191718912. Its totient is φ = 191663412.

The previous prime is 191691151. The next prime is 191691169. The reversal of 191691161 is 161196191.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 191691161 - 2²² = 187496857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191691169) 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 in 3 ways as a sum of consecutive naturals, for example, 5576 + ... + 20358.

It is an arithmetic number, because the mean of its divisors is an integer number (47929728).

Almost surely, 2^191691161 is an apocalyptic number.

It is an amenable number.

191691161 is a deficient number, since it is larger than the sum of its proper divisors (27751).

191691161 is a wasteful number, since it uses less digits than its factorization.

191691161 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27750.

The product of its digits is 2916, while the sum is 35.

The square root of 191691161 is about 13845.2577079663. The cubic root of 191691161 is about 576.5903406542.

The spelling of 191691161 in words is "one hundred ninety-one million, six hundred ninety-one thousand, one hundred sixty-one".