28705249 has 4 divisors (see below), whose sum is σ = 28746900. Its totient is φ = 28663600.

The previous prime is 28705223. The next prime is 28705253. The reversal of 28705249 is 94250782.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 94250782 = 2 ⋅47125391.

It can be written as a sum of positive squares in 2 ways, for example, as 19360000 + 9345249 = 4400^2 + 3057^2 .

It is a cyclic number.

It is not a de Polignac number, because 28705249 - 2⁵ = 28705217 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28705049) 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, 19774 + ... + 21175.

It is an arithmetic number, because the mean of its divisors is an integer number (7186725).

Almost surely, 2^28705249 is an apocalyptic number.

It is an amenable number.

28705249 is a deficient number, since it is larger than the sum of its proper divisors (41651).

28705249 is an equidigital number, since it uses as much as digits as its factorization.

28705249 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41650.

The product of its (nonzero) digits is 40320, while the sum is 37.

The square root of 28705249 is about 5357.7279699514. The cubic root of 28705249 is about 306.1872527840.

The spelling of 28705249 in words is "twenty-eight million, seven hundred five thousand, two hundred forty-nine".