21120111 has 12 divisors (see below), whose sum is σ = 30703192.
Its totient is φ = 13989456.
The previous prime is 21120109. The next prime is 21120119. The reversal of 21120111 is 11102112.
It is a happy number.
It is not a de Polignac number, because 21120111 - 21 = 21120109 is a prime.
It is a Harshad number since it is a multiple of its sum of digits (9).
It is a Duffinian number.
It is a junction number, because it is equal to n+sod(n) for n = 21120093 and 21120102.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (21120119) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (11) of ones.
It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6061 + ... + 8886.
Almost surely, 221120111 is an apocalyptic number.
21120111 is a deficient number, since it is larger than the sum of its proper divisors (9583081).
21120111 is a wasteful number, since it uses less digits than its factorization.
21120111 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 15110 (or 15107 counting only the distinct ones).
The product of its (nonzero) digits is 4, while the sum is 9.
The square root of 21120111 is about 4595.6621938519.
The cubic root of 21120111 is about 276.4174134527.
Adding to 21120111 its reverse (11102112), we get a palindrome (32222223).
The spelling of 21120111 in words is "twenty-one million, one hundred twenty thousand, one hundred eleven".