28172785 has 4 divisors (see below), whose sum is σ = 33807348. Its totient is φ = 22538224.

The previous prime is 28172759. The next prime is 28172803. The reversal of 28172785 is 58727182.

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 4397409 + 23775376 = 2097^2 + 4876^2 .

It is a cyclic number.

It is not a de Polignac number, because 28172785 - 2⁷ = 28172657 is a prime.

It is a Smith number, since the sum of its digits (40) 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.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2817274 + ... + 2817283.

It is an arithmetic number, because the mean of its divisors is an integer number (8451837).

Almost surely, 2^28172785 is an apocalyptic number.

It is an amenable number.

28172785 is a deficient number, since it is larger than the sum of its proper divisors (5634563).

28172785 is an equidigital number, since it uses as much as digits as its factorization.

28172785 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5634562.

The product of its digits is 62720, while the sum is 40.

The square root of 28172785 is about 5307.8041599140. The cubic root of 28172785 is about 304.2822322690.

The spelling of 28172785 in words is "twenty-eight million, one hundred seventy-two thousand, seven hundred eighty-five".