21212211111 has 32 divisors (see below), whose sum is σ = 35750604288. Its totient is φ = 10886451840.

The previous prime is 21212211103. The next prime is 21212211121. The reversal of 21212211111 is 11111221212.

It is a happy number.

It is not a de Polignac number, because 21212211111 - 2³ = 21212211103 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21212211121) 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, 1039905 + ... + 1060106.

It is an arithmetic number, because the mean of its divisors is an integer number (1117206384).

Almost surely, 2^21212211111 is an apocalyptic number.

21212211111 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21212211111 is a deficient number, since it is larger than the sum of its proper divisors (14538393177).

21212211111 is a wasteful number, since it uses less digits than its factorization.

21212211111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2100071.

The product of its digits is 16, while the sum is 15.

Adding to 21212211111 its reverse (11111221212), we get a palindrome (32323432323).

The spelling of 21212211111 in words is "twenty-one billion, two hundred twelve million, two hundred eleven thousand, one hundred eleven".