191591 has 4 divisors (see below), whose sum is σ = 192552. Its totient is φ = 190632.

The previous prime is 191579. The next prime is 191599. The reversal of 191591 is 195191.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 195191 = 47 ⋅4153.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-191591 is a prime.

It is a super-2 number, since 2×191591² = 73414222562, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 191591.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 191591.

It is not an unprimeable number, because it can be changed into a prime (191599) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 56 + ... + 621.

It is an arithmetic number, because the mean of its divisors is an integer number (48138).

2¹⁹¹⁵⁹¹ is an apocalyptic number.

191591 is a deficient number, since it is larger than the sum of its proper divisors (961).

191591 is an equidigital number, since it uses as much as digits as its factorization.

191591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 960.

The product of its digits is 405, while the sum is 26.

The square root of 191591 is about 437.7110919317. The cubic root of 191591 is about 57.6489897966.

Subtracting 191591 from its reverse (195191), we obtain a square (3600 = 60²).

The spelling of 191591 in words is "one hundred ninety-one thousand, five hundred ninety-one".