21121212111111 has 48 divisors (see below), whose sum is σ = 35013882968064. Its totient is φ = 12018376035072.

The previous prime is 21121212111071. The next prime is 21121212111119. The reversal of 21121212111111 is 11111121212112.

21121212111111 is a `hidden beast` number, since 211 + 21 + 212 + 111 + 111 = 666.

It is not a de Polignac number, because 21121212111111 - 2⁷ = 21121212110983 is a prime.

It is a super-2 number, since 2×21121212111111² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121212111119) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 39783570 + ... + 40310976.

It is an arithmetic number, because the mean of its divisors is an integer number (729455895168).

Almost surely, 2^{21121212111111} is an apocalyptic number.

21121212111111 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

21121212111111 is a deficient number, since it is larger than the sum of its proper divisors (13892670856953).

21121212111111 is a wasteful number, since it uses less digits than its factorization.

21121212111111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530100 (or 530097 counting only the distinct ones).

The product of its digits is 16, while the sum is 18.

Adding to 21121212111111 its reverse (11111121212112), we get a palindrome (32232333323223).

The spelling of 21121212111111 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twelve million, one hundred eleven thousand, one hundred eleven".