28561509 has 24 divisors (see below), whose sum is σ = 42911232. Its totient is φ = 18286560.

The previous prime is 28561501. The next prime is 28561531. The reversal of 28561509 is 90516582.

It is a happy number.

It is not a de Polignac number, because 28561509 - 2³ = 28561501 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28561501) 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 23 ways as a sum of consecutive naturals, for example, 46287 + ... + 46899.

It is an arithmetic number, because the mean of its divisors is an integer number (1787968).

Almost surely, 2^28561509 is an apocalyptic number.

It is an amenable number.

28561509 is a deficient number, since it is larger than the sum of its proper divisors (14349723).

28561509 is a wasteful number, since it uses less digits than its factorization.

28561509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 817 (or 814 counting only the distinct ones).

The product of its (nonzero) digits is 21600, while the sum is 36.

The square root of 28561509 is about 5344.2968667543. The cubic root of 28561509 is about 305.6753252469.

The spelling of 28561509 in words is "twenty-eight million, five hundred sixty-one thousand, five hundred nine".