21212211 has 32 divisors (see below), whose sum is σ = 30643200. Its totient is φ = 13029120.

The previous prime is 21212197. The next prime is 21212239. The reversal of 21212211 is 11221212.

It is not a de Polignac number, because 21212211 - 2⁵ = 21212179 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21212281) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 268470 + ... + 268548.

It is an arithmetic number, because the mean of its divisors is an integer number (957600).

Almost surely, 2^21212211 is an apocalyptic number.

21212211 is a deficient number, since it is larger than the sum of its proper divisors (9430989).

21212211 is a wasteful number, since it uses less digits than its factorization.

21212211 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 219.

The product of its digits is 16, while the sum is 12.

The square root of 21212211 is about 4605.6716122624. The cubic root of 21212211 is about 276.8186286356.

Adding to 21212211 its reverse (11221212), we get a palindrome (32433423).

Subtracting from 21212211 its reverse (11221212), we obtain a palindrome (9990999).

The spelling of 21212211 in words is "twenty-one million, two hundred twelve thousand, two hundred eleven".