28180321 has 4 divisors (see below), whose sum is σ = 30348052. Its totient is φ = 26012592.

The previous prime is 28180319. The next prime is 28180357. The reversal of 28180321 is 12308182.

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 9388096 + 18792225 = 3064^2 + 4335^2 .

It is a cyclic number.

It is not a de Polignac number, because 28180321 - 2¹ = 28180319 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28180381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1083846 + ... + 1083871.

It is an arithmetic number, because the mean of its divisors is an integer number (7587013).

Almost surely, 2^28180321 is an apocalyptic number.

It is an amenable number.

28180321 is a deficient number, since it is larger than the sum of its proper divisors (2167731).

28180321 is a wasteful number, since it uses less digits than its factorization.

28180321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2167730.

The product of its (nonzero) digits is 768, while the sum is 25.

The square root of 28180321 is about 5308.5140105306. The cubic root of 28180321 is about 304.3093608906.

The spelling of 28180321 in words is "twenty-eight million, one hundred eighty thousand, three hundred twenty-one".