21320402321 has 4 divisors (see below), whose sum is σ = 22574543652. Its totient is φ = 20066260992.

The previous prime is 21320402261. The next prime is 21320402377. The reversal of 21320402321 is 12320402312.

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 7737665296 + 13582737025 = 87964^2 + 116545^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21320402321 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21320402293 and 21320402302.

It is not an unprimeable number, because it can be changed into a prime (21320402821) 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, 627070640 + ... + 627070673.

It is an arithmetic number, because the mean of its divisors is an integer number (5643635913).

Almost surely, 2^21320402321 is an apocalyptic number.

It is an amenable number.

21320402321 is a deficient number, since it is larger than the sum of its proper divisors (1254141331).

21320402321 is a wasteful number, since it uses less digits than its factorization.

21320402321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1254141330.

The product of its (nonzero) digits is 576, while the sum is 20.

Adding to 21320402321 its reverse (12320402312), we get a palindrome (33640804633).

Subtracting from 21320402321 its reverse (12320402312), we obtain a palindrome (9000000009).

The spelling of 21320402321 in words is "twenty-one billion, three hundred twenty million, four hundred two thousand, three hundred twenty-one".