21373 has 8 divisors (see below), whose sum is σ = 24480. Its totient is φ = 18480.

The previous prime is 21347. The next prime is 21377. The reversal of 21373 is 37312.

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

It is not a de Polignac number, because 21373 - 2⁵ = 21341 is a prime.

It is a Duffinian number.

21373 is a lucky number.

It is a nialpdrome in base 13.

It is a congruent 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, 286 + ... + 352.

It is an arithmetic number, because the mean of its divisors is an integer number (3060).

2²¹³⁷³ is an apocalyptic number.

It is an amenable number.

21373 is a deficient number, since it is larger than the sum of its proper divisors (3107).

21373 is a wasteful number, since it uses less digits than its factorization.

21373 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 107.

The product of its digits is 126, while the sum is 16.

The square root of 21373 is about 146.1950751564. The cubic root of 21373 is about 27.7516299127.

Adding to 21373 its reverse (37312), we get a palindrome (58685).

The spelling of 21373 in words is "twenty-one thousand, three hundred seventy-three", and thus it is an iban number.