21022321 has 4 divisors (see below), whose sum is σ = 21310372. Its totient is φ = 20734272.

The previous prime is 21022279. The next prime is 21022357. The reversal of 21022321 is 12322012.

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 5340721 + 15681600 = 2311^2 + 3960^2 .

It is a cyclic number.

It is not a de Polignac number, because 21022321 - 2⁷ = 21022193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21022021) 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, 143916 + ... + 144061.

It is an arithmetic number, because the mean of its divisors is an integer number (5327593).

Almost surely, 2^21022321 is an apocalyptic number.

It is an amenable number.

21022321 is a deficient number, since it is larger than the sum of its proper divisors (288051).

21022321 is an equidigital number, since it uses as much as digits as its factorization.

21022321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 288050.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21022321 is about 4585.0104689084. The cubic root of 21022321 is about 275.9901321474.

Adding to 21022321 its reverse (12322012), we get a palindrome (33344333).

The spelling of 21022321 in words is "twenty-one million, twenty-two thousand, three hundred twenty-one".