231213531 has 8 divisors (see below), whose sum is σ = 318229504. Its totient is φ = 149169960.

The previous prime is 231213497. The next prime is 231213551. The reversal of 231213531 is 135312132.

231213531 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It is not a de Polignac number, because 231213531 - 2⁶ = 231213467 is a prime.

It is a super-2 number, since 2×231213531² = 106919393834975922, 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 = 231213498 and 231213507.

It is not an unprimeable number, because it can be changed into a prime (231213551) 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, 1242991 + ... + 1243176.

It is an arithmetic number, because the mean of its divisors is an integer number (39778688).

Almost surely, 2^231213531 is an apocalyptic number.

231213531 is a deficient number, since it is larger than the sum of its proper divisors (87015973).

231213531 is a wasteful number, since it uses less digits than its factorization.

231213531 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2486201.

The product of its digits is 540, while the sum is 21.

The square root of 231213531 is about 15205.7071851328. The cubic root of 231213531 is about 613.7682451786.

Adding to 231213531 its reverse (135312132), we get a palindrome (366525663).

The spelling of 231213531 in words is "two hundred thirty-one million, two hundred thirteen thousand, five hundred thirty-one".