28509047 has 4 divisors (see below), whose sum is σ = 32581776. Its totient is φ = 24436320.

The previous prime is 28509011. The next prime is 28509049. The reversal of 28509047 is 74090582.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 28509047 - 2²⁰ = 27460471 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 28508998 and 28509016.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28509049) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2036354 + ... + 2036367.

It is an arithmetic number, because the mean of its divisors is an integer number (8145444).

Almost surely, 2^28509047 is an apocalyptic number.

28509047 is a deficient number, since it is larger than the sum of its proper divisors (4072729).

28509047 is an equidigital number, since it uses as much as digits as its factorization.

28509047 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4072728.

The product of its (nonzero) digits is 20160, while the sum is 35.

The square root of 28509047 is about 5339.3863879663. The cubic root of 28509047 is about 305.4880549419.

The spelling of 28509047 in words is "twenty-eight million, five hundred nine thousand, forty-seven".