21722213 has 2 divisors, whose sum is σ = 21722214. Its totient is φ = 21722212.

The previous prime is 21722203. The next prime is 21722221. The reversal of 21722213 is 31222712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13300609 + 8421604 = 3647^2 + 2902^2 .

It is a cyclic number.

It is not a de Polignac number, because 21722213 - 2¹⁴ = 21705829 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21722203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10861106 + 10861107.

It is an arithmetic number, because the mean of its divisors is an integer number (10861107).

Almost surely, 2^21722213 is an apocalyptic number.

It is an amenable number.

21722213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21722213 is an equidigital number, since it uses as much as digits as its factorization.

21722213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 336, while the sum is 20.

The square root of 21722213 is about 4660.7094953451. The cubic root of 21722213 is about 279.0195855608.

Adding to 21722213 its reverse (31222712), we get a palindrome (52944925).

The spelling of 21722213 in words is "twenty-one million, seven hundred twenty-two thousand, two hundred thirteen".