28171705 has 4 divisors (see below), whose sum is σ = 33806052. Its totient is φ = 22537360.

The previous prime is 28171697. The next prime is 28171729. The reversal of 28171705 is 50717182.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 50717182 = 2 ⋅25358591.

It can be written as a sum of positive squares in 2 ways, for example, as 19386409 + 8785296 = 4403^2 + 2964^2 .

It is not a de Polignac number, because 28171705 - 2³ = 28171697 is a prime.

It is a Smith number, since the sum of its digits (31) 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 pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2817166 + ... + 2817175.

It is an arithmetic number, because the mean of its divisors is an integer number (8451513).

Almost surely, 2^28171705 is an apocalyptic number.

It is an amenable number.

28171705 is a deficient number, since it is larger than the sum of its proper divisors (5634347).

28171705 is an equidigital number, since it uses as much as digits as its factorization.

28171705 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5634346.

The product of its (nonzero) digits is 3920, while the sum is 31.

The square root of 28171705 is about 5307.7024219525. The cubic root of 28171705 is about 304.2783440129.

Adding to 28171705 its reverse (50717182), we get a palindrome (78888887).

The spelling of 28171705 in words is "twenty-eight million, one hundred seventy-one thousand, seven hundred five".