21110 has 8 divisors (see below), whose sum is σ = 38016. Its totient is φ = 8440.

The previous prime is 21107. The next prime is 21121. The reversal of 21110 is 1112.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Harshad number since it is a multiple of its sum of digits (5).

It is an Ulam number.

It is a Curzon number.

It is a plaindrome in base 14.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 21094 and 21103.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1046 + ... + 1065.

It is an arithmetic number, because the mean of its divisors is an integer number (4752).

2²¹¹¹⁰ is an apocalyptic number.

21110 is a deficient number, since it is larger than the sum of its proper divisors (16906).

21110 is a wasteful number, since it uses less digits than its factorization.

21110 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2118.

The product of its (nonzero) digits is 2, while the sum is 5.

The square root of 21110 is about 145.2928078055. The cubic root of 21110 is about 27.6373295904.

Adding to 21110 its reverse (1112), we get a palindrome (22222).

It can be divided in two parts, 21 and 110, that added together give a palindrome (131).

The spelling of 21110 in words is "twenty-one thousand, one hundred ten", and thus it is an iban number.