231311111221 has 4 divisors (see below), whose sum is σ = 231355335744. Its totient is φ = 231266886700.

The previous prime is 231311111197. The next prime is 231311111243. The reversal of 231311111221 is 122111113132.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 231311111221 - 2⁵ = 231311111189 is a prime.

It is a super-2 number, since 2×231311111221² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (237311111221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22104415 + ... + 22114876.

It is an arithmetic number, because the mean of its divisors is an integer number (57838833936).

Almost surely, 2^231311111221 is an apocalyptic number.

It is an amenable number.

231311111221 is a deficient number, since it is larger than the sum of its proper divisors (44224523).

231311111221 is an equidigital number, since it uses as much as digits as its factorization.

231311111221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44224522.

The product of its digits is 72, while the sum is 19.

Adding to 231311111221 its reverse (122111113132), we get a palindrome (353422224353).

The spelling of 231311111221 in words is "two hundred thirty-one billion, three hundred eleven million, one hundred eleven thousand, two hundred twenty-one".