205831 has 4 divisors (see below), whose sum is σ = 211432. Its totient is φ = 200232.

The previous prime is 205823. The next prime is 205837. The reversal of 205831 is 138502.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 205831 - 2³ = 205823 is a prime.

It is a super-2 number, since 2×205831² = 84732801122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 205799 and 205808.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (205837) 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 3 ways as a sum of consecutive naturals, for example, 2745 + ... + 2818.

It is an arithmetic number, because the mean of its divisors is an integer number (52858).

2²⁰⁵⁸³¹ is an apocalyptic number.

205831 is a deficient number, since it is larger than the sum of its proper divisors (5601).

205831 is an equidigital number, since it uses as much as digits as its factorization.

205831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5600.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 205831 is about 453.6860147723. The cubic root of 205831 is about 59.0432508682.

The spelling of 205831 in words is "two hundred five thousand, eight hundred thirty-one".