231331209 has 16 divisors (see below), whose sum is σ = 312947712. Its totient is φ = 151977488.

The previous prime is 231331201. The next prime is 231331211. The reversal of 231331209 is 902133132.

It is a cyclic number.

It is not a de Polignac number, because 231331209 - 2³ = 231331201 is a prime.

It is not an unprimeable number, because it can be changed into a prime (231331201) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 124324 + ... + 126170.

It is an arithmetic number, because the mean of its divisors is an integer number (19559232).

Almost surely, 2^231331209 is an apocalyptic number.

It is an amenable number.

231331209 is a deficient number, since it is larger than the sum of its proper divisors (81616503).

231331209 is a wasteful number, since it uses less digits than its factorization.

231331209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2436.

The product of its (nonzero) digits is 972, while the sum is 24.

The square root of 231331209 is about 15209.5762268381. The cubic root of 231331209 is about 613.8723549586.

It can be divided in two parts, 231331 and 209, that added together give a triangular number (231540 = T₆₈₀).

The spelling of 231331209 in words is "two hundred thirty-one million, three hundred thirty-one thousand, two hundred nine".