21231231231 has 32 divisors (see below), whose sum is σ = 33028028928. Its totient is φ = 11880512640.

The previous prime is 21231231227. The next prime is 21231231247. The reversal of 21231231231 is 13213213212.

It is not a de Polignac number, because 21231231231 - 2² = 21231231227 is a prime.

It is a super-2 number, since 2×21231231231² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21231231198 and 21231231207.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231231211) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 254281 + ... + 327293.

It is an arithmetic number, because the mean of its divisors is an integer number (1032125904).

Almost surely, 2^21231231231 is an apocalyptic number.

21231231231 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21231231231 is a deficient number, since it is larger than the sum of its proper divisors (11796797697).

21231231231 is a wasteful number, since it uses less digits than its factorization.

21231231231 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 73311.

The product of its digits is 432, while the sum is 21.

Adding to 21231231231 its reverse (13213213212), we get a palindrome (34444444443).

The spelling of 21231231231 in words is "twenty-one billion, two hundred thirty-one million, two hundred thirty-one thousand, two hundred thirty-one".