21210213 has 32 divisors (see below), whose sum is σ = 31190400. Its totient is φ = 12773376.

The previous prime is 21210197. The next prime is 21210221. The reversal of 21210213 is 31201212.

It is not a de Polignac number, because 21210213 - 2⁴ = 21210197 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210283) 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 31 ways as a sum of consecutive naturals, for example, 187645 + ... + 187757.

It is an arithmetic number, because the mean of its divisors is an integer number (974700).

Almost surely, 2^21210213 is an apocalyptic number.

It is an amenable number.

21210213 is a deficient number, since it is larger than the sum of its proper divisors (9980187).

21210213 is a wasteful number, since it uses less digits than its factorization.

21210213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21210213 is about 4605.4547006783. The cubic root of 21210213 is about 276.8099370855.

Adding to 21210213 its reverse (31201212), we get a palindrome (52411425).

Subtracting 21210213 from its reverse (31201212), we obtain a palindrome (9990999).

The spelling of 21210213 in words is "twenty-one million, two hundred ten thousand, two hundred thirteen".