28005 has 8 divisors (see below), whose sum is σ = 44832. Its totient is φ = 14928.

The previous prime is 28001. The next prime is 28019. The reversal of 28005 is 50082.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 28005 - 2² = 28001 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15), and also a Moran number because the ratio is a prime number: 1867 = 28005 / (2 + 8 + 0 + 0 + 5).

It is a nialpdrome in base 13.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28001) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 919 + ... + 948.

It is an arithmetic number, because the mean of its divisors is an integer number (5604).

2²⁸⁰⁰⁵ is an apocalyptic number.

It is an amenable number.

28005 is a deficient number, since it is larger than the sum of its proper divisors (16827).

28005 is a wasteful number, since it uses less digits than its factorization.

28005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1875.

The product of its (nonzero) digits is 80, while the sum is 15.

The square root of 28005 is about 167.3469449975. The cubic root of 28005 is about 30.3676971046.

Adding to 28005 its reverse (50082), we get a palindrome (78087).

The spelling of 28005 in words is "twenty-eight thousand, five".