231211531 has 8 divisors (see below), whose sum is σ = 232721424. Its totient is φ = 229706400.

The previous prime is 231211507. The next prime is 231211549. The reversal of 231211531 is 135112132.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 231211531 - 2⁵ = 231211499 is a prime.

It is a super-2 number, since 2×231211531² = 106917544134727922, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 231211499 and 231211508.

It is not an unprimeable number, because it can be changed into a prime (231211031) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 158401 + ... + 159853.

It is an arithmetic number, because the mean of its divisors is an integer number (29090178).

Almost surely, 2^231211531 is an apocalyptic number.

231211531 is a deficient number, since it is larger than the sum of its proper divisors (1509893).

231211531 is a wasteful number, since it uses less digits than its factorization.

231211531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2381.

The product of its digits is 180, while the sum is 19.

The square root of 231211531 is about 15205.6414202098. The cubic root of 231211531 is about 613.7664754725.

Adding to 231211531 its reverse (135112132), we get a palindrome (366323663).

The spelling of 231211531 in words is "two hundred thirty-one million, two hundred eleven thousand, five hundred thirty-one".