21371 has 8 divisors (see below), whose sum is σ = 25344. Its totient is φ = 17640.

The previous prime is 21347. The next prime is 21377. The reversal of 21371 is 17312.

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

It is not a de Polignac number, because 21371 - 2¹⁰ = 20347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21377) 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, 266 + ... + 336.

It is an arithmetic number, because the mean of its divisors is an integer number (3168).

2²¹³⁷¹ is an apocalyptic number.

21371 is a deficient number, since it is larger than the sum of its proper divisors (3973).

21371 is an equidigital number, since it uses as much as digits as its factorization.

21371 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 121.

The product of its digits is 42, while the sum is 14.

The square root of 21371 is about 146.1882348207. The cubic root of 21371 is about 27.7507642567.

Adding to 21371 its reverse (17312), we get a palindrome (38683).

The spelling of 21371 in words is "twenty-one thousand, three hundred seventy-one", and thus it is an iban number.