21938 has 8 divisors (see below), whose sum is σ = 37632. Its totient is φ = 9396.

The previous prime is 21937. The next prime is 21943. The reversal of 21938 is 83912.

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

It is a plaindrome in base 15.

It is not an unprimeable number, because it can be changed into a prime (21937) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 770 + ... + 797.

It is an arithmetic number, because the mean of its divisors is an integer number (4704).

2²¹⁹³⁸ is an apocalyptic number.

21938 is a deficient number, since it is larger than the sum of its proper divisors (15694).

21938 is a wasteful number, since it uses less digits than its factorization.

21938 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1576.

The product of its digits is 432, while the sum is 23.

The square root of 21938 is about 148.1148203253. The cubic root of 21938 is about 27.9940463532.

It can be divided in two parts, 21 and 938, that added together give a palindrome (959).

The spelling of 21938 in words is "twenty-one thousand, nine hundred thirty-eight".