21382 has 4 divisors (see below), whose sum is σ = 32076. Its totient is φ = 10690.

The previous prime is 21379. The next prime is 21383. The reversal of 21382 is 28312.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21383) 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 as a sum of consecutive naturals, namely, 5344 + ... + 5347.

It is an arithmetic number, because the mean of its divisors is an integer number (8019).

2²¹³⁸² is an apocalyptic number.

21382 is a deficient number, since it is larger than the sum of its proper divisors (10694).

21382 is a wasteful number, since it uses less digits than its factorization.

21382 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10693.

The product of its digits is 96, while the sum is 16.

The square root of 21382 is about 146.2258527074. The cubic root of 21382 is about 27.7555246961.

Adding to 21382 its reverse (28312), we get a palindrome (49694).

The spelling of 21382 in words is "twenty-one thousand, three hundred eighty-two".