231231221 has 8 divisors (see below), whose sum is σ = 249199104. Its totient is φ = 213289200.

The previous prime is 231231199. The next prime is 231231251. The reversal of 231231221 is 122132132.

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 231231221 - 2¹⁸ = 230969077 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 231231221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231231251) 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, 14696 + ... + 26046.

It is an arithmetic number, because the mean of its divisors is an integer number (31149888).

Almost surely, 2^231231221 is an apocalyptic number.

It is an amenable number.

231231221 is a deficient number, since it is larger than the sum of its proper divisors (17967883).

231231221 is a wasteful number, since it uses less digits than its factorization.

231231221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12931.

The product of its digits is 144, while the sum is 17.

The square root of 231231221 is about 15206.2888634933. The cubic root of 231231221 is about 613.7838977853.

Adding to 231231221 its reverse (122132132), we get a palindrome (353363353).

It can be divided in two parts, 2312 and 31221, that added together give a palindrome (33533).

The spelling of 231231221 in words is "two hundred thirty-one million, two hundred thirty-one thousand, two hundred twenty-one".