28189321 has 4 divisors (see below), whose sum is σ = 28332612. Its totient is φ = 28046032.

The previous prime is 28189309. The next prime is 28189393. The reversal of 28189321 is 12398182.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15515721 + 12673600 = 3939^2 + 3560^2 .

It is a cyclic number.

It is not a de Polignac number, because 28189321 - 2¹¹ = 28187273 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28189921) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 71350 + ... + 71743.

It is an arithmetic number, because the mean of its divisors is an integer number (7083153).

Almost surely, 2^28189321 is an apocalyptic number.

It is an amenable number.

28189321 is a deficient number, since it is larger than the sum of its proper divisors (143291).

28189321 is a wasteful number, since it uses less digits than its factorization.

28189321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 143290.

The product of its digits is 6912, while the sum is 34.

The square root of 28189321 is about 5309.3616377113. The cubic root of 28189321 is about 304.3417533858.

The spelling of 28189321 in words is "twenty-eight million, one hundred eighty-nine thousand, three hundred twenty-one".