231311211021 has 18 divisors (see below), whose sum is σ = 367251685710. Its totient is φ = 140188612080.

The previous prime is 231311211017. The next prime is 231311211029. The reversal of 231311211021 is 120112113132.

231311211021 is a `hidden beast` number, since 231 + 311 + 21 + 102 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 154654214121 + 76656996900 = 393261^2 + 276870^2 .

It is not a de Polignac number, because 231311211021 - 2² = 231311211017 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 231311210985 and 231311211003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231311211029) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 106202406 + ... + 106204583.

Almost surely, 2^231311211021 is an apocalyptic number.

It is an amenable number.

231311211021 is a deficient number, since it is larger than the sum of its proper divisors (135940474689).

231311211021 is a wasteful number, since it uses less digits than its factorization.

231311211021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 212407017 (or 212407003 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

Adding to 231311211021 its reverse (120112113132), we get a palindrome (351423324153).

The spelling of 231311211021 in words is "two hundred thirty-one billion, three hundred eleven million, two hundred eleven thousand, twenty-one".