28221 has 8 divisors (see below), whose sum is σ = 39360. Its totient is φ = 17952.

The previous prime is 28219. The next prime is 28229. The reversal of 28221 is 12282.

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

It is not a de Polignac number, because 28221 - 2¹ = 28219 is a prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 28221.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 28221.

It is not an unprimeable number, because it can be changed into a prime (28229) 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, 136 + ... + 273.

It is an arithmetic number, because the mean of its divisors is an integer number (4920).

2²⁸²²¹ is an apocalyptic number.

It is an amenable number.

28221 is a deficient number, since it is larger than the sum of its proper divisors (11139).

28221 is a wasteful number, since it uses less digits than its factorization.

28221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 435.

The product of its digits is 64, while the sum is 15.

The square root of 28221 is about 167.9910711913. The cubic root of 28221 is about 30.4455716555.

It can be divided in two parts, 282 and 21, that added together give a palindrome (303).

The spelling of 28221 in words is "twenty-eight thousand, two hundred twenty-one".