21213111111 has 16 divisors (see below), whose sum is σ = 28548153600. Its totient is φ = 14010192000.

The previous prime is 21213111109. The next prime is 21213111121. The reversal of 21213111111 is 11111131212.

It is not a de Polignac number, because 21213111111 - 2¹ = 21213111109 is a prime.

21213111111 is a modest number, since divided by 111111 gives 21213 as remainder.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21213111121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 749190 + ... + 776988.

It is an arithmetic number, because the mean of its divisors is an integer number (1784259600).

Almost surely, 2^21213111111 is an apocalyptic number.

21213111111 is a deficient number, since it is larger than the sum of its proper divisors (7335042489).

21213111111 is a wasteful number, since it uses less digits than its factorization.

21213111111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30166.

The product of its digits is 12, while the sum is 15.

Adding to 21213111111 its reverse (11111131212), we get a palindrome (32324242323).

The spelling of 21213111111 in words is "twenty-one billion, two hundred thirteen million, one hundred eleven thousand, one hundred eleven".