28328509 has 4 divisors (see below), whose sum is σ = 30903840. Its totient is φ = 25753180.

The previous prime is 28328501. The next prime is 28328527. The reversal of 28328509 is 90582382.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28328509 - 2³ = 28328501 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28328501) 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, 1287649 + ... + 1287670.

It is an arithmetic number, because the mean of its divisors is an integer number (7725960).

Almost surely, 2^28328509 is an apocalyptic number.

It is an amenable number.

28328509 is a deficient number, since it is larger than the sum of its proper divisors (2575331).

28328509 is a wasteful number, since it uses less digits than its factorization.

28328509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2575330.

The product of its (nonzero) digits is 34560, while the sum is 37.

The square root of 28328509 is about 5322.4532877236. The cubic root of 28328509 is about 304.8418386284.

The spelling of 28328509 in words is "twenty-eight million, three hundred twenty-eight thousand, five hundred nine".