21111021111 has 32 divisors (see below), whose sum is σ = 29475956736. Its totient is φ = 13424400000.

The previous prime is 21111021101. The next prime is 21111021131. The reversal of 21111021111 is 11112011112.

It is not a de Polignac number, because 21111021111 - 2¹⁷ = 21110890039 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111021101) 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, 2127261 + ... + 2137161.

It is an arithmetic number, because the mean of its divisors is an integer number (921123648).

Almost surely, 2^21111021111 is an apocalyptic number.

21111021111 is a deficient number, since it is larger than the sum of its proper divisors (8364935625).

21111021111 is a wasteful number, since it uses less digits than its factorization.

21111021111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10263.

The product of its (nonzero) digits is 4, while the sum is 12.

Adding to 21111021111 its reverse (11112011112), we get a palindrome (32223032223).

Subtracting from 21111021111 its reverse (11112011112), we obtain a palindrome (9999009999).

It can be divided in two parts, 211110 and 21111, that added together give a triangular number (232221 = T₆₈₁).

The spelling of 21111021111 in words is "twenty-one billion, one hundred eleven million, twenty-one thousand, one hundred eleven".