21302321 has 2 divisors, whose sum is σ = 21302322. Its totient is φ = 21302320.

The previous prime is 21302299. The next prime is 21302371. The reversal of 21302321 is 12320312.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21298225 + 4096 = 4615^2 + 64^2 .

It is a cyclic number.

It is not a de Polignac number, because 21302321 - 2¹⁸ = 21040177 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21302296 and 21302305.

It is not a weakly prime, because it can be changed into another prime (21302371) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651160 + 10651161.

It is an arithmetic number, because the mean of its divisors is an integer number (10651161).

Almost surely, 2^21302321 is an apocalyptic number.

It is an amenable number.

21302321 is a deficient number, since it is larger than the sum of its proper divisors (1).

21302321 is an equidigital number, since it uses as much as digits as its factorization.

21302321 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21302321 is about 4615.4437489802. The cubic root of 21302321 is about 277.2100523720.

Adding to 21302321 its reverse (12320312), we get a palindrome (33622633).

Subtracting from 21302321 its reverse (12320312), we obtain a square (8982009 = 2997²).

The spelling of 21302321 in words is "twenty-one million, three hundred two thousand, three hundred twenty-one".