21226213 has 2 divisors, whose sum is σ = 21226214. Its totient is φ = 21226212.

The previous prime is 21226199. The next prime is 21226237. The reversal of 21226213 is 31262212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21224449 + 1764 = 4607^2 + 42^2 .

It is a cyclic number.

It is not a de Polignac number, because 21226213 - 2⁵ = 21226181 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21226613) 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, 10613106 + 10613107.

It is an arithmetic number, because the mean of its divisors is an integer number (10613107).

Almost surely, 2^21226213 is an apocalyptic number.

It is an amenable number.

21226213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21226213 is an equidigital number, since it uses as much as digits as its factorization.

21226213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 19.

The square root of 21226213 is about 4607.1914438191. The cubic root of 21226213 is about 276.8795237793.

Adding to 21226213 its reverse (31262212), we get a palindrome (52488425).

The spelling of 21226213 in words is "twenty-one million, two hundred twenty-six thousand, two hundred thirteen".