231189509 has 4 divisors (see below), whose sum is σ = 233573004. Its totient is φ = 228806016.

The previous prime is 231189493. The next prime is 231189527. The reversal of 231189509 is 905981132.

231189509 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.

It can be written as a sum of positive squares in 2 ways, for example, as 115627009 + 115562500 = 10753^2 + 10750^2 .

It is a cyclic number.

It is not a de Polignac number, because 231189509 - 2⁴ = 231189493 is a prime.

It is a super-2 number, since 2×231189509² = 106897178143322162, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231189559) 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, 1191602 + ... + 1191795.

It is an arithmetic number, because the mean of its divisors is an integer number (58393251).

Almost surely, 2^231189509 is an apocalyptic number.

It is an amenable number.

231189509 is a deficient number, since it is larger than the sum of its proper divisors (2383495).

231189509 is an equidigital number, since it uses as much as digits as its factorization.

231189509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2383494.

The product of its (nonzero) digits is 19440, while the sum is 38.

The square root of 231189509 is about 15204.9172638328. The cubic root of 231189509 is about 613.7469885631.

The spelling of 231189509 in words is "two hundred thirty-one million, one hundred eighty-nine thousand, five hundred nine".