21111020111111 has 4 divisors (see below), whose sum is σ = 24126880126992. Its totient is φ = 18095160095232.

The previous prime is 21111020111011. The next prime is 21111020111117. The reversal of 21111020111111 is 11111102011112.

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 21111020111111 - 2¹⁸ = 21111019848967 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 (21111020111117) 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, 1507930007930 + ... + 1507930007943.

It is an arithmetic number, because the mean of its divisors is an integer number (6031720031748).

Almost surely, 2^{21111020111111} is an apocalyptic number.

21111020111111 is a deficient number, since it is larger than the sum of its proper divisors (3015860015881).

21111020111111 is an equidigital number, since it uses as much as digits as its factorization.

21111020111111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3015860015880.

The product of its (nonzero) digits is 4, while the sum is 14.

Adding to 21111020111111 its reverse (11111102011112), we get a palindrome (32222122122223).

It can be divided in two parts, 2111102011111 and 1, that added together give a palindrome (2111102011112).

The spelling of 21111020111111 in words is "twenty-one trillion, one hundred eleven billion, twenty million, one hundred eleven thousand, one hundred eleven".