21212311 has 12 divisors (see below), whose sum is σ = 23319720. Its totient is φ = 19268480.

The previous prime is 21212297. The next prime is 21212353. The reversal of 21212311 is 11321212.

It is not a de Polignac number, because 21212311 - 2⁷ = 21212183 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21212291 and 21212300.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212111) 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 11 ways as a sum of consecutive naturals, for example, 7116 + ... + 9646.

It is an arithmetic number, because the mean of its divisors is an integer number (1943310).

Almost surely, 2^21212311 is an apocalyptic number.

21212311 is a deficient number, since it is larger than the sum of its proper divisors (2107409).

21212311 is a wasteful number, since it uses less digits than its factorization.

21212311 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2594 (or 2577 counting only the distinct ones).

The product of its digits is 24, while the sum is 13.

The square root of 21212311 is about 4605.6824684296. The cubic root of 21212311 is about 276.8190636338.

Adding to 21212311 its reverse (11321212), we get a palindrome (32533523).

The spelling of 21212311 in words is "twenty-one million, two hundred twelve thousand, three hundred eleven".