231809 has 2 divisors, whose sum is σ = 231810. Its totient is φ = 231808.

The previous prime is 231799. The next prime is 231821. The reversal of 231809 is 908132.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 222784 + 9025 = 472^2 + 95^2 .

It is a cyclic number.

It is not a de Polignac number, because 231809 - 2¹⁶ = 166273 is a prime.

It is a Chen prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 231809.

It is not a weakly prime, because it can be changed into another prime (231839) 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 as a sum of consecutive naturals, namely, 115904 + 115905.

It is an arithmetic number, because the mean of its divisors is an integer number (115905).

2²³¹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

231809 is a deficient number, since it is larger than the sum of its proper divisors (1).

231809 is an equidigital number, since it uses as much as digits as its factorization.

231809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 231809 is about 481.4654712438. The cubic root of 231809 is about 61.4294694556.

The spelling of 231809 in words is "two hundred thirty-one thousand, eight hundred nine".