21321233121 has 4 divisors (see below), whose sum is σ = 28428310832. Its totient is φ = 14214155412.

The previous prime is 21321233117. The next prime is 21321233137. The reversal of 21321233121 is 12133212312.

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 not a de Polignac number, because 21321233121 - 2² = 21321233117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21321233161) 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, 3553538851 + ... + 3553538856.

It is an arithmetic number, because the mean of its divisors is an integer number (7107077708).

Almost surely, 2^21321233121 is an apocalyptic number.

It is an amenable number.

21321233121 is a deficient number, since it is larger than the sum of its proper divisors (7107077711).

21321233121 is an equidigital number, since it uses as much as digits as its factorization.

21321233121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7107077710.

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

Adding to 21321233121 its reverse (12133212312), we get a palindrome (33454445433).

The spelling of 21321233121 in words is "twenty-one billion, three hundred twenty-one million, two hundred thirty-three thousand, one hundred twenty-one".