191661517 has 4 divisors (see below), whose sum is σ = 196841596. Its totient is φ = 186481440.

The previous prime is 191661469. The next prime is 191661521. The reversal of 191661517 is 715166191.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 166771396 + 24890121 = 12914^2 + 4989^2 .

It is a cyclic number.

It is not a de Polignac number, because 191661517 - 2¹¹ = 191659469 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (37), and also a Moran number because the ratio is a prime number: 5180041 = 191661517 / (1 + 9 + 1 + 6 + 6 + 1 + 5 + 1 + 7).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191661017) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2589984 + ... + 2590057.

It is an arithmetic number, because the mean of its divisors is an integer number (49210399).

Almost surely, 2^191661517 is an apocalyptic number.

It is an amenable number.

191661517 is a deficient number, since it is larger than the sum of its proper divisors (5180079).

191661517 is an equidigital number, since it uses as much as digits as its factorization.

191661517 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5180078.

The product of its digits is 11340, while the sum is 37.

The square root of 191661517 is about 13844.1871195098. The cubic root of 191661517 is about 576.5606169307.

The spelling of 191661517 in words is "one hundred ninety-one million, six hundred sixty-one thousand, five hundred seventeen".