21012213 has 16 divisors (see below), whose sum is σ = 28929600. Its totient is φ = 13557120.

The previous prime is 21012193. The next prime is 21012227. The reversal of 21012213 is 31221012.

It is not a de Polignac number, because 21012213 - 2⁵ = 21012181 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012283) 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 in 15 ways as a sum of consecutive naturals, for example, 16483 + ... + 17711.

It is an arithmetic number, because the mean of its divisors is an integer number (1808100).

Almost surely, 2^21012213 is an apocalyptic number.

It is an amenable number.

21012213 is a deficient number, since it is larger than the sum of its proper divisors (7917387).

21012213 is a wasteful number, since it uses less digits than its factorization.

21012213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1412.

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

The square root of 21012213 is about 4583.9080488160. The cubic root of 21012213 is about 275.9458909891.

Adding to 21012213 its reverse (31221012), we get a palindrome (52233225).

The spelling of 21012213 in words is "twenty-one million, twelve thousand, two hundred thirteen".