21031120321 has 4 divisors (see below), whose sum is σ = 21112953732. Its totient is φ = 20949286912.

The previous prime is 21031120261. The next prime is 21031120337. The reversal of 21031120321 is 12302113012.

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 10741249600 + 10289870721 = 103640^2 + 101439^2 .

It is a cyclic number.

It is not a de Polignac number, because 21031120321 - 2⁷ = 21031120193 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21031120295 and 21031120304.

It is not an unprimeable number, because it can be changed into a prime (21031120021) 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, 40916320 + ... + 40916833.

It is an arithmetic number, because the mean of its divisors is an integer number (5278238433).

Almost surely, 2^21031120321 is an apocalyptic number.

It is an amenable number.

21031120321 is a deficient number, since it is larger than the sum of its proper divisors (81833411).

21031120321 is an equidigital number, since it uses as much as digits as its factorization.

21031120321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81833410.

The product of its (nonzero) digits is 72, while the sum is 16.

Adding to 21031120321 its reverse (12302113012), we get a palindrome (33333233333).

The spelling of 21031120321 in words is "twenty-one billion, thirty-one million, one hundred twenty thousand, three hundred twenty-one".