21231233431 has 4 divisors (see below), whose sum is σ = 21234468112. Its totient is φ = 21227998752.

The previous prime is 21231233423. The next prime is 21231233449. The reversal of 21231233431 is 13433213212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21231233431 - 2³ = 21231233423 is a prime.

It is a super-2 number, since 2×21231233431² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21231233396 and 21231233405.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21231239431) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1607475 + ... + 1620628.

It is an arithmetic number, because the mean of its divisors is an integer number (5308617028).

Almost surely, 2^21231233431 is an apocalyptic number.

21231233431 is a deficient number, since it is larger than the sum of its proper divisors (3234681).

21231233431 is an equidigital number, since it uses as much as digits as its factorization.

21231233431 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3234680.

The product of its digits is 2592, while the sum is 25.

Adding to 21231233431 its reverse (13433213212), we get a palindrome (34664446643).

The spelling of 21231233431 in words is "twenty-one billion, two hundred thirty-one million, two hundred thirty-three thousand, four hundred thirty-one".