21112 has 32 divisors (see below), whose sum is σ = 50400. Its totient is φ = 8064.

The previous prime is 21107. The next prime is 21121.

21112 is nontrivially palindromic in base 10.

It is a Harshad number since it is a multiple of its sum of digits (7).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a junction number, because it is equal to n+sod(n) for n = 21095 and 21104.

It is a congruent number.

It is an unprimeable number.

21112 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 714 + ... + 742.

It is an arithmetic number, because the mean of its divisors is an integer number (1575).

2²¹¹¹² is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21112, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25200).

21112 is an abundant number, since it is smaller than the sum of its proper divisors (29288).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21112 is a wasteful number, since it uses less digits than its factorization.

21112 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55 (or 51 counting only the distinct ones).

The product of its digits is 4, while the sum is 7.

The square root of 21112 is about 145.2996902956. The cubic root of 21112 is about 27.6382023665.

The spelling of 21112 in words is "twenty-one thousand, one hundred twelve", and thus it is an iban number.