21060 has 60 divisors (see below), whose sum is σ = 71148. Its totient is φ = 5184.

The previous prime is 21059. The next prime is 21061. The reversal of 21060 is 6012.

It is an interprime number because it is at equal distance from previous prime (21059) and next prime (21061).

It can be written as a sum of positive squares in 2 ways, for example, as 5184 + 15876 = 72^2 + 126^2 .

It is a tau number, because it is divible by the number of its divisors (60).

It is a Harshad number since it is a multiple of its sum of digits (9).

It is a Saint-Exupery number, since it is equal to the product of the sides of a Pythagorean triangle: 39 × 15 × 36.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 1614 + ... + 1626.

2²¹⁰⁶⁰ is an apocalyptic number.

21060 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21060, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35574).

21060 is an abundant number, since it is smaller than the sum of its proper divisors (50088).

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

21060 is a wasteful number, since it uses less digits than its factorization.

21060 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34 (or 23 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 9.

The square root of 21060 is about 145.1206394694. The cubic root of 21060 is about 27.6154922475.

Adding to 21060 its reverse (6012), we get a palindrome (27072).

The spelling of 21060 in words is "twenty-one thousand, sixty".