21052213 has 12 divisors (see below), whose sum is σ = 26373900. Its totient is φ = 16656192.

The previous prime is 21052177. The next prime is 21052217. The reversal of 21052213 is 31225012.

It can be written as a sum of positive squares in 2 ways, for example, as 1044484 + 20007729 = 1022^2 + 4473^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21052213 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21052217) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 15888 + ... + 17161.

It is an arithmetic number, because the mean of its divisors is an integer number (2197825).

Almost surely, 2^21052213 is an apocalyptic number.

It is an amenable number.

21052213 is a deficient number, since it is larger than the sum of its proper divisors (5321687).

21052213 is a wasteful number, since it uses less digits than its factorization.

21052213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33076 (or 33069 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 16.

The square root of 21052213 is about 4588.2690636012. The cubic root of 21052213 is about 276.1208819013.

Adding to 21052213 its reverse (31225012), we get a palindrome (52277225).

The spelling of 21052213 in words is "twenty-one million, fifty-two thousand, two hundred thirteen".