191665 has 4 divisors (see below), whose sum is σ = 230004. Its totient is φ = 153328.

The previous prime is 191657. The next prime is 191669. The reversal of 191665 is 566191.

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 99856 + 91809 = 316^2 + 303^2 .

It is a cyclic number.

It is not a de Polignac number, because 191665 - 2³ = 191657 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (191669) 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, 19162 + ... + 19171.

It is an arithmetic number, because the mean of its divisors is an integer number (57501).

2¹⁹¹⁶⁶⁵ is an apocalyptic number.

It is an amenable number.

191665 is a deficient number, since it is larger than the sum of its proper divisors (38339).

191665 is an equidigital number, since it uses as much as digits as its factorization.

191665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38338.

The product of its digits is 1620, while the sum is 28.

The square root of 191665 is about 437.7956144138. The cubic root of 191665 is about 57.6564109457.

The spelling of 191665 in words is "one hundred ninety-one thousand, six hundred sixty-five".