28318309 has 4 divisors (see below), whose sum is σ = 28578220. Its totient is φ = 28058400.

The previous prime is 28318307. The next prime is 28318319. The reversal of 28318309 is 90381382.

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 22118209 + 6200100 = 4703^2 + 2490^2 .

It is a cyclic number.

It is not a de Polignac number, because 28318309 - 2¹ = 28318307 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28318307) 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, 129792 + ... + 130009.

It is an arithmetic number, because the mean of its divisors is an integer number (7144555).

Almost surely, 2^28318309 is an apocalyptic number.

It is an amenable number.

28318309 is a deficient number, since it is larger than the sum of its proper divisors (259911).

28318309 is a wasteful number, since it uses less digits than its factorization.

28318309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259910.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 28318309 is about 5321.4949967091. The cubic root of 28318309 is about 304.8052469859.

The spelling of 28318309 in words is "twenty-eight million, three hundred eighteen thousand, three hundred nine".