191891 has 8 divisors (see below), whose sum is σ = 222720. Its totient is φ = 161928.

The previous prime is 191861. The next prime is 191899. The reversal of 191891 is 198191.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 191891 - 2⁶ = 191827 is a prime.

It is a pancake number, because a pancake can be divided into 191891 parts by 619 straight cuts.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (191899) 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 7 ways as a sum of consecutive naturals, for example, 380 + ... + 726.

It is an arithmetic number, because the mean of its divisors is an integer number (27840).

2¹⁹¹⁸⁹¹ is an apocalyptic number.

191891 is a deficient number, since it is larger than the sum of its proper divisors (30829).

191891 is an equidigital number, since it uses as much as digits as its factorization.

191891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 433.

The product of its digits is 648, while the sum is 29.

The square root of 191891 is about 438.0536496823. The cubic root of 191891 is about 57.6790637178.

The spelling of 191891 in words is "one hundred ninety-one thousand, eight hundred ninety-one".