28658209 has 4 divisors (see below), whose sum is σ = 30344004. Its totient is φ = 26972416.

The previous prime is 28658191. The next prime is 28658219. The reversal of 28658209 is 90285682.

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 22043025 + 6615184 = 4695^2 + 2572^2 .

It is a cyclic number.

It is not a de Polignac number, because 28658209 - 2⁹ = 28657697 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28658219) 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, 842872 + ... + 842905.

It is an arithmetic number, because the mean of its divisors is an integer number (7586001).

Almost surely, 2^28658209 is an apocalyptic number.

It is an amenable number.

28658209 is a deficient number, since it is larger than the sum of its proper divisors (1685795).

28658209 is a wasteful number, since it uses less digits than its factorization.

28658209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1685794.

The product of its (nonzero) digits is 69120, while the sum is 40.

The square root of 28658209 is about 5353.3362494803. The cubic root of 28658209 is about 306.0199091379.

The spelling of 28658209 in words is "twenty-eight million, six hundred fifty-eight thousand, two hundred nine".