205891 has 8 divisors (see below), whose sum is σ = 239360. Its totient is φ = 173448.

The previous prime is 205883. The next prime is 205913. The reversal of 205891 is 198502.

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 205891 - 2³ = 205883 is a prime.

It is a super-2 number, since 2×205891² = 84782207762, which contains 22 as substring.

It is a Duffinian number.

205891 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (205391) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 250 + ... + 688.

It is an arithmetic number, because the mean of its divisors is an integer number (29920).

2²⁰⁵⁸⁹¹ is an apocalyptic number.

205891 is a deficient number, since it is larger than the sum of its proper divisors (33469).

205891 is an equidigital number, since it uses as much as digits as its factorization.

205891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 513.

The product of its (nonzero) digits is 720, while the sum is 25.

The square root of 205891 is about 453.7521349812. The cubic root of 205891 is about 59.0489873719.

The spelling of 205891 in words is "two hundred five thousand, eight hundred ninety-one".