28240509 has 32 divisors (see below), whose sum is σ = 42791040. Its totient is φ = 16416000.

The previous prime is 28240493. The next prime is 28240529. The reversal of 28240509 is 90504282.

It is not a de Polignac number, because 28240509 - 2⁴ = 28240493 is a prime.

It is a Smith number, since the sum of its digits (30) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28240529) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 123207 + ... + 123435.

It is an arithmetic number, because the mean of its divisors is an integer number (1337220).

Almost surely, 2^28240509 is an apocalyptic number.

It is an amenable number.

28240509 is a deficient number, since it is larger than the sum of its proper divisors (14550531).

28240509 is a wasteful number, since it uses less digits than its factorization.

28240509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 381.

The product of its (nonzero) digits is 5760, while the sum is 30.

The square root of 28240509 is about 5314.1799931880. The cubic root of 28240509 is about 304.5258565030.

The spelling of 28240509 in words is "twenty-eight million, two hundred forty thousand, five hundred nine".