28257305 has 4 divisors (see below), whose sum is σ = 33908772. Its totient is φ = 22605840.

The previous prime is 28257287. The next prime is 28257311. The reversal of 28257305 is 50375282.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8826841 + 19430464 = 2971^2 + 4408^2 .

It is not a de Polignac number, because 28257305 - 2¹⁴ = 28240921 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2825726 + ... + 2825735.

It is an arithmetic number, because the mean of its divisors is an integer number (8477193).

Almost surely, 2^28257305 is an apocalyptic number.

It is an amenable number.

28257305 is a deficient number, since it is larger than the sum of its proper divisors (5651467).

28257305 is an equidigital number, since it uses as much as digits as its factorization.

28257305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5651466.

The product of its (nonzero) digits is 16800, while the sum is 32.

The square root of 28257305 is about 5315.7600585429. The cubic root of 28257305 is about 304.5862166356.

The spelling of 28257305 in words is "twenty-eight million, two hundred fifty-seven thousand, three hundred five".