21335213 has 4 divisors (see below), whose sum is σ = 22070940. Its totient is φ = 20599488.

The previous prime is 21335207. The next prime is 21335219. The reversal of 21335213 is 31253312.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (21335207) and next prime (21335219).

It can be written as a sum of positive squares in 2 ways, for example, as 3374569 + 17960644 = 1837^2 + 4238^2 .

It is a cyclic number.

It is not a de Polignac number, because 21335213 - 2¹⁰ = 21334189 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 (21335219) 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, 367820 + ... + 367877.

It is an arithmetic number, because the mean of its divisors is an integer number (5517735).

Almost surely, 2^21335213 is an apocalyptic number.

It is an amenable number.

21335213 is a deficient number, since it is larger than the sum of its proper divisors (735727).

21335213 is an equidigital number, since it uses as much as digits as its factorization.

21335213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 735726.

The product of its digits is 540, while the sum is 20.

The square root of 21335213 is about 4619.0056289206. The cubic root of 21335213 is about 277.3526550515.

Adding to 21335213 its reverse (31253312), we get a palindrome (52588525).

The spelling of 21335213 in words is "twenty-one million, three hundred thirty-five thousand, two hundred thirteen".