21084 has 24 divisors (see below), whose sum is σ = 56448. Its totient is φ = 6000.

The previous prime is 21067. The next prime is 21089. The reversal of 21084 is 48012.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 21084.

It is not an unprimeable number, because it can be changed into a prime (21089) by changing a digit.

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, 42 + ... + 209.

It is an arithmetic number, because the mean of its divisors is an integer number (2352).

2²¹⁰⁸⁴ is an apocalyptic number.

It is an amenable number.

21084 is an abundant number, since it is smaller than the sum of its proper divisors (35364).

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 (28224).

21084 is a wasteful number, since it uses less digits than its factorization.

21084 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265 (or 263 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 15.

The square root of 21084 is about 145.2033057475. The cubic root of 21084 is about 27.6259784807.

Adding to 21084 its reverse (48012), we get a palindrome (69096).

It can be divided in two parts, 2108 and 4, that added together give a palindrome (2112).

The spelling of 21084 in words is "twenty-one thousand, eighty-four".