21329 has 8 divisors (see below), whose sum is σ = 26688. Its totient is φ = 16560.

The previous prime is 21323. The next prime is 21341. The reversal of 21329 is 92312.

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

It is a cyclic number.

It is not a de Polignac number, because 21329 - 2⁴ = 21313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21323) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 62 + ... + 215.

It is an arithmetic number, because the mean of its divisors is an integer number (3336).

2²¹³²⁹ is an apocalyptic number.

It is an amenable number.

21329 is a deficient number, since it is larger than the sum of its proper divisors (5359).

21329 is a wasteful number, since it uses less digits than its factorization.

21329 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 295.

The product of its digits is 108, while the sum is 17.

The square root of 21329 is about 146.0445137621. The cubic root of 21329 is about 27.7325729934.

Subtracting from 21329 its sum of digits (17), we obtain a palindrome (21312).

It can be divided in two parts, 213 and 29, that added together give a palindrome (242).

The spelling of 21329 in words is "twenty-one thousand, three hundred twenty-nine".