28521 has 6 divisors (see below), whose sum is σ = 41210.
Its totient is φ = 19008.
The previous prime is 28517. The next prime is 28537. The reversal of 28521 is 12582.
28521 is nontrivially palindromic in base 5.
It can be written as a sum of positive squares in only one way, i.e., 27225 + 1296 = 165^2 + 36^2
It is not a de Polignac number, because 28521 - 22 = 28517 is a prime.
It is a Duffinian number.
It is a nialpdrome in base 9.
It is a junction number, because it is equal to n+sod(n) for n = 28494 and 28503.
It is not an unprimeable number, because it can be changed into a prime (28541) by changing a digit.
It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1576 + ... + 1593.
228521 is an apocalyptic number.
It is an amenable number.
28521 is a deficient number, since it is larger than the sum of its proper divisors (12689).
28521 is a wasteful number, since it uses less digits than its factorization.
28521 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 3175 (or 3172 counting only the distinct ones).
The product of its digits is 160, while the sum is 18.
The square root of 28521 is about 168.8816153405.
The cubic root of 28521 is about 30.5530743011.
The spelling of 28521 in words is "twenty-eight thousand, five hundred twenty-one".