21302213 has 4 divisors (see below), whose sum is σ = 21513228. Its totient is φ = 21091200.

The previous prime is 21302191. The next prime is 21302219. The reversal of 21302213 is 31220312.

It is a happy number.

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 9351364 + 11950849 = 3058^2 + 3457^2 .

It is a cyclic number.

It is not a de Polignac number, because 21302213 - 2⁸ = 21301957 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21302219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 105356 + ... + 105557.

It is an arithmetic number, because the mean of its divisors is an integer number (5378307).

Almost surely, 2^21302213 is an apocalyptic number.

It is an amenable number.

21302213 is a deficient number, since it is larger than the sum of its proper divisors (211015).

21302213 is a wasteful number, since it uses less digits than its factorization.

21302213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 211014.

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

The square root of 21302213 is about 4615.4320491152. The cubic root of 21302213 is about 277.2095838982.

Adding to 21302213 its reverse (31220312), we get a palindrome (52522525).

The spelling of 21302213 in words is "twenty-one million, three hundred two thousand, two hundred thirteen".