21331212111 has 32 divisors (see below), whose sum is σ = 36502617600. Its totient is φ = 12167533440.

The previous prime is 21331212109. The next prime is 21331212113. The reversal of 21331212111 is 11121213312.

It is an interprime number because it is at equal distance from previous prime (21331212109) and next prime (21331212113).

It is not a de Polignac number, because 21331212111 - 2¹ = 21331212109 is a prime.

It is a super-2 number, since 2×21331212111² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21331212113) 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, 2107371 + ... + 2117468.

It is an arithmetic number, because the mean of its divisors is an integer number (1140706800).

Almost surely, 2^21331212111 is an apocalyptic number.

21331212111 is a deficient number, since it is larger than the sum of its proper divisors (15171405489).

21331212111 is a wasteful number, since it uses less digits than its factorization.

21331212111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4224876 (or 4224870 counting only the distinct ones).

The product of its digits is 72, while the sum is 18.

Adding to 21331212111 its reverse (11121213312), we get a palindrome (32452425423).

The spelling of 21331212111 in words is "twenty-one billion, three hundred thirty-one million, two hundred twelve thousand, one hundred eleven".