243909 has 12 divisors (see below), whose sum is σ = 361452. Its totient is φ = 158400.

The previous prime is 243889. The next prime is 243911. The reversal of 243909 is 909342.

It can be written as a sum of positive squares in 2 ways, for example, as 91809 + 152100 = 303^2 + 390^2 .

It is not a de Polignac number, because 243909 - 2⁷ = 243781 is a prime.

It is a d-powerful number, because it can be written as 2⁷ + 4⁵ + 9⁴ + 3¹¹ + 0 + 9⁵ .

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (243989) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 39 + ... + 699.

It is an arithmetic number, because the mean of its divisors is an integer number (30121).

2²⁴³⁹⁰⁹ is an apocalyptic number.

It is an amenable number.

243909 is a deficient number, since it is larger than the sum of its proper divisors (117543).

243909 is a wasteful number, since it uses less digits than its factorization.

243909 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 708 (or 705 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 27.

The square root of 243909 is about 493.8714407617. The cubic root of 243909 is about 62.4802284127.

The spelling of 243909 in words is "two hundred forty-three thousand, nine hundred nine".