231209 has 4 divisors (see below), whose sum is σ = 252240. Its totient is φ = 210180.

The previous prime is 231197. The next prime is 231223. The reversal of 231209 is 902132.

231209 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 231209 - 2¹² = 227113 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (231269) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 10499 + ... + 10520.

It is an arithmetic number, because the mean of its divisors is an integer number (63060).

2²³¹²⁰⁹ is an apocalyptic number.

It is an amenable number.

231209 is a deficient number, since it is larger than the sum of its proper divisors (21031).

231209 is a wasteful number, since it uses less digits than its factorization.

231209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21030.

The product of its (nonzero) digits is 108, while the sum is 17.

The square root of 231209 is about 480.8419698820. The cubic root of 231209 is about 61.3764235895.

The spelling of 231209 in words is "two hundred thirty-one thousand, two hundred nine".