28705 has 4 divisors (see below), whose sum is σ = 34452. Its totient is φ = 22960.

The previous prime is 28703. The next prime is 28711. The reversal of 28705 is 50782.

28705 = 49² + 50² + ... + 58².

28705 is nontrivially palindromic in base 9 and base 12.

28705 is digitally balanced in base 6, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50782 = 2 ⋅25391.

It can be written as a sum of positive squares in 2 ways, for example, as 12321 + 16384 = 111^2 + 128^2 .

It is not a de Polignac number, because 28705 - 2¹ = 28703 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

28705 is strictly pandigital in base 6.

It is a nialpdrome in base 14.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28703) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2866 + ... + 2875.

It is an arithmetic number, because the mean of its divisors is an integer number (8613).

2²⁸⁷⁰⁵ is an apocalyptic number.

It is an amenable number.

28705 is a deficient number, since it is larger than the sum of its proper divisors (5747).

28705 is an equidigital number, since it uses as much as digits as its factorization.

28705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5746.

The product of its (nonzero) digits is 560, while the sum is 22.

The square root of 28705 is about 169.4254998517. The cubic root of 28705 is about 30.6186367454.

The spelling of 28705 in words is "twenty-eight thousand, seven hundred five".