21333 has 8 divisors (see below), whose sum is σ = 30688. Its totient is φ = 13104.

The previous prime is 21323. The next prime is 21341. The reversal of 21333 is 33312.

It is a happy number.

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

It is not a de Polignac number, because 21333 - 2⁴ = 21317 is a prime.

It is a Duffinian number.

21333 is a modest number, since divided by 333 gives 21 as remainder.

It is a Curzon number.

It is a plaindrome in base 14.

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 (21313) 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, 235 + ... + 312.

It is an arithmetic number, because the mean of its divisors is an integer number (3836).

2²¹³³³ is an apocalyptic number.

It is an amenable number.

21333 is a deficient number, since it is larger than the sum of its proper divisors (9355).

21333 is a wasteful number, since it uses less digits than its factorization.

21333 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 563.

The product of its digits is 54, while the sum is 12.

The square root of 21333 is about 146.0582075749. The cubic root of 21333 is about 27.7343065230.

Subtracting from 21333 its sum of digits (12), we obtain a triangular number (21321 = T₂₀₆).

Adding to 21333 its reverse (33312), we get a palindrome (54645).

The spelling of 21333 in words is "twenty-one thousand, three hundred thirty-three".