243809 has 2 divisors, whose sum is σ = 243810. Its totient is φ = 243808.

The previous prime is 243799. The next prime is 243829. The reversal of 243809 is 908342.

243809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 222784 + 21025 = 472^2 + 145^2 .

It is a cyclic number.

It is not a de Polignac number, because 243809 - 2⁸ = 243553 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (243829) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 121904 + 121905.

It is an arithmetic number, because the mean of its divisors is an integer number (121905).

2²⁴³⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

243809 is a deficient number, since it is larger than the sum of its proper divisors (1).

243809 is an equidigital number, since it uses as much as digits as its factorization.

243809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 26.

The square root of 243809 is about 493.7701894606. The cubic root of 243809 is about 62.4716885106.

It can be divided in two parts, 24380 and 9, that added together give a cube (24389 = 29³).

The spelling of 243809 in words is "two hundred forty-three thousand, eight hundred nine".