21180 has 24 divisors (see below), whose sum is σ = 59472. Its totient is φ = 5632.

The previous prime is 21179. The next prime is 21187. The reversal of 21180 is 8112.

It is a happy number.

21180 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is a nialpdrome in base 13 and base 15.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21187) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 117 + ... + 236.

It is an arithmetic number, because the mean of its divisors is an integer number (2478).

2²¹¹⁸⁰ is an apocalyptic number.

21180 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21180 is an abundant number, since it is smaller than the sum of its proper divisors (38292).

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 (29736).

21180 is a wasteful number, since it uses less digits than its factorization.

21180 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 365 (or 363 counting only the distinct ones).

The product of its (nonzero) digits is 16, while the sum is 12.

The square root of 21180 is about 145.5335012978. The cubic root of 21180 is about 27.6678440169.

Adding to 21180 its reverse (8112), we get a palindrome (29292).

The spelling of 21180 in words is "twenty-one thousand, one hundred eighty".