205391 has 2 divisors, whose sum is σ = 205392. Its totient is φ = 205390.

The previous prime is 205357. The next prime is 205397. The reversal of 205391 is 193502.

205391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 205391 - 2⁶ = 205327 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (205397) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 102695 + 102696.

It is an arithmetic number, because the mean of its divisors is an integer number (102696).

205391 is a Friedman number, since it can be written as 59^3+10+2, using all its digits and the basic arithmetic operations.

2²⁰⁵³⁹¹ is an apocalyptic number.

205391 is a deficient number, since it is larger than the sum of its proper divisors (1).

205391 is an equidigital number, since it uses as much as digits as its factorization.

205391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 270, while the sum is 20.

The square root of 205391 is about 453.2008384811. The cubic root of 205391 is about 59.0011490727.

Adding to 205391 its reverse (193502), we get a palindrome (398893).

The spelling of 205391 in words is "two hundred five thousand, three hundred ninety-one".