21102 has 8 divisors (see below), whose sum is σ = 42216. Its totient is φ = 7032.

The previous prime is 21101. The next prime is 21107. The reversal of 21102 is 20112.

It is a happy number.

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

21102 is an admirable number.

It is a Harshad number since it is a multiple of its sum of digits (6), and also a Moran number because the ratio is a prime number: 3517 = 21102 / (2 + 1 + 1 + 0 + 2).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21101) 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, 1753 + ... + 1764.

It is an arithmetic number, because the mean of its divisors is an integer number (5277).

2²¹¹⁰² is an apocalyptic number.

21102 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21108).

21102 is a wasteful number, since it uses less digits than its factorization.

21102 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3522.

The product of its (nonzero) digits is 4, while the sum is 6.

The square root of 21102 is about 145.2652745841. The cubic root of 21102 is about 27.6338379344.

Adding to 21102 its reverse (20112), we get a palindrome (41214).

Subtracting from 21102 its reverse (20112), we obtain a triangular number (990 = T₄₄).

It can be divided in two parts, 2110 and 2, that added together give a palindrome (2112).

The spelling of 21102 in words is "twenty-one thousand, one hundred two", and thus it is an iban number.