28644509 has 4 divisors (see below), whose sum is σ = 28928220. Its totient is φ = 28360800.

The previous prime is 28644491. The next prime is 28644523. The reversal of 28644509 is 90544682.

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 18062500 + 10582009 = 4250^2 + 3253^2 .

It is not a de Polignac number, because 28644509 - 2¹⁶ = 28578973 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28644569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141704 + ... + 141905.

It is an arithmetic number, because the mean of its divisors is an integer number (7232055).

Almost surely, 2^28644509 is an apocalyptic number.

It is an amenable number.

28644509 is a deficient number, since it is larger than the sum of its proper divisors (283711).

28644509 is a wasteful number, since it uses less digits than its factorization.

28644509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 283710.

The product of its (nonzero) digits is 69120, while the sum is 38.

The square root of 28644509 is about 5352.0565206283. The cubic root of 28644509 is about 305.9711372951.

The spelling of 28644509 in words is "twenty-eight million, six hundred forty-four thousand, five hundred nine".