21224131321 has 4 divisors (see below), whose sum is σ = 22472609652. Its totient is φ = 19975652992.

The previous prime is 21224131303. The next prime is 21224131339. The reversal of 21224131321 is 12313142212.

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

It is an interprime number because it is at equal distance from previous prime (21224131303) and next prime (21224131339).

It can be written as a sum of positive squares in 2 ways, for example, as 15230274921 + 5993856400 = 123411^2 + 77420^2 .

It is a cyclic number.

It is not a de Polignac number, because 21224131321 - 2⁵ = 21224131289 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21224131292 and 21224131301.

It is not an unprimeable number, because it can be changed into a prime (21224131391) 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, 624239140 + ... + 624239173.

It is an arithmetic number, because the mean of its divisors is an integer number (5618152413).

Almost surely, 2^21224131321 is an apocalyptic number.

It is an amenable number.

21224131321 is a deficient number, since it is larger than the sum of its proper divisors (1248478331).

21224131321 is a wasteful number, since it uses less digits than its factorization.

21224131321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1248478330.

The product of its digits is 576, while the sum is 22.

Adding to 21224131321 its reverse (12313142212), we get a palindrome (33537273533).

The spelling of 21224131321 in words is "twenty-one billion, two hundred twenty-four million, one hundred thirty-one thousand, three hundred twenty-one".