21321131321 has 12 divisors (see below), whose sum is σ = 24928042788. Its totient is φ = 18182479392.

The previous prime is 21321131317. The next prime is 21321131327. The reversal of 21321131321 is 12313112312.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 20712966400 + 608164921 = 143920^2 + 24661^2 .

It is not a de Polignac number, because 21321131321 - 2² = 21321131317 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21321131293 and 21321131302.

It is not an unprimeable number, because it can be changed into a prime (21321131327) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1094726 + ... + 1114031.

It is an arithmetic number, because the mean of its divisors is an integer number (2077336899).

Almost surely, 2^21321131321 is an apocalyptic number.

It is an amenable number.

21321131321 is a deficient number, since it is larger than the sum of its proper divisors (3606911467).

21321131321 is a wasteful number, since it uses less digits than its factorization.

21321131321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2208968 (or 2208961 counting only the distinct ones).

The product of its digits is 216, while the sum is 20.

Adding to 21321131321 its reverse (12313112312), we get a palindrome (33634243633).

The spelling of 21321131321 in words is "twenty-one billion, three hundred twenty-one million, one hundred thirty-one thousand, three hundred twenty-one".