21171 has 4 divisors (see below), whose sum is σ = 28232. Its totient is φ = 14112.

The previous prime is 21169. The next prime is 21179. The reversal of 21171 is 17112.

21171 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 21171 - 2¹ = 21169 is a prime.

It is a super-2 number, since 2×21171² = 896422482, which contains 22 as substring.

It is a D-number.

It is the 146-th Hogben number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21179) by changing a digit.

It is a nontrivial repunit in base 145.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3526 + ... + 3531.

It is an arithmetic number, because the mean of its divisors is an integer number (7058).

2²¹¹⁷¹ is an apocalyptic number.

21171 is a deficient number, since it is larger than the sum of its proper divisors (7061).

21171 is an equidigital number, since it uses as much as digits as its factorization.

21171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7060.

The product of its digits is 14, while the sum is 12.

The square root of 21171 is about 145.5025772968. The cubic root of 21171 is about 27.6639245036.

Adding to 21171 its reverse (17112), we get a palindrome (38283).

It can be divided in two parts, 211 and 71, that added together give a palindrome (282).

The spelling of 21171 in words is "twenty-one thousand, one hundred seventy-one", and thus it is an iban number.