21112100111 has 4 divisors (see below), whose sum is σ = 21627029424. Its totient is φ = 20597170800.

The previous prime is 21112100101. The next prime is 21112100161. The reversal of 21112100111 is 11100121112.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21112100111 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21112100092 and 21112100101.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21112100101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 257464595 + ... + 257464676.

It is an arithmetic number, because the mean of its divisors is an integer number (5406757356).

Almost surely, 2^21112100111 is an apocalyptic number.

21112100111 is a deficient number, since it is larger than the sum of its proper divisors (514929313).

21112100111 is an equidigital number, since it uses as much as digits as its factorization.

21112100111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 514929312.

The product of its (nonzero) digits is 4, while the sum is 11.

Adding to 21112100111 its reverse (11100121112), we get a palindrome (32212221223).

The spelling of 21112100111 in words is "twenty-one billion, one hundred twelve million, one hundred thousand, one hundred eleven".