28447509 has 4 divisors (see below), whose sum is σ = 37930016. Its totient is φ = 18965004.

The previous prime is 28447493. The next prime is 28447537. The reversal of 28447509 is 90574482.

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 not a de Polignac number, because 28447509 - 2⁴ = 28447493 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 (28447609) 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, 4741249 + ... + 4741254.

It is an arithmetic number, because the mean of its divisors is an integer number (9482504).

Almost surely, 2^28447509 is an apocalyptic number.

It is an amenable number.

28447509 is a deficient number, since it is larger than the sum of its proper divisors (9482507).

28447509 is an equidigital number, since it uses as much as digits as its factorization.

28447509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9482506.

The product of its (nonzero) digits is 80640, while the sum is 39.

The square root of 28447509 is about 5333.6206276787. The cubic root of 28447509 is about 305.2680935801.

The spelling of 28447509 in words is "twenty-eight million, four hundred forty-seven thousand, five hundred nine".