21111100111 has 4 divisors (see below), whose sum is σ = 21316062352. Its totient is φ = 20906137872.

The previous prime is 21111100103. The next prime is 21111100117. The reversal of 21111100111 is 11100111112.

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

It is a cyclic number.

It is not a de Polignac number, because 21111100111 - 2³ = 21111100103 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111100117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 102480966 + ... + 102481171.

It is an arithmetic number, because the mean of its divisors is an integer number (5329015588).

Almost surely, 2^21111100111 is an apocalyptic number.

21111100111 is a deficient number, since it is larger than the sum of its proper divisors (204962241).

21111100111 is a wasteful number, since it uses less digits than its factorization.

21111100111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204962240.

The product of its (nonzero) digits is 2, while the sum is 10.

Adding to 21111100111 its reverse (11100111112), we get a palindrome (32211211223).

The spelling of 21111100111 in words is "twenty-one billion, one hundred eleven million, one hundred thousand, one hundred eleven".