21312323233 has 4 divisors (see below), whose sum is σ = 21312667780. Its totient is φ = 21311978688.

The previous prime is 21312323191. The next prime is 21312323243. The reversal of 21312323233 is 33232321312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 6568778304 + 14743544929 = 81048^2 + 121423^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21312323233 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21312323198 and 21312323207.

It is not an unprimeable number, because it can be changed into a prime (21312323243) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 51060 + ... + 212677.

It is an arithmetic number, because the mean of its divisors is an integer number (5328166945).

Almost surely, 2^21312323233 is an apocalyptic number.

It is an amenable number.

21312323233 is a deficient number, since it is larger than the sum of its proper divisors (344547).

21312323233 is an equidigital number, since it uses as much as digits as its factorization.

21312323233 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 344546.

The product of its digits is 3888, while the sum is 25.

Adding to 21312323233 its reverse (33232321312), we get a palindrome (54544644545).

The spelling of 21312323233 in words is "twenty-one billion, three hundred twelve million, three hundred twenty-three thousand, two hundred thirty-three".