28391705 has 4 divisors (see below), whose sum is σ = 34070052. Its totient is φ = 22713360.

The previous prime is 28391687. The next prime is 28391707. The reversal of 28391705 is 50719382.

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 5914624 + 22477081 = 2432^2 + 4741^2 .

It is a de Polignac number, because none of the positive numbers 2^k-28391705 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (28391707) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2839166 + ... + 2839175.

It is an arithmetic number, because the mean of its divisors is an integer number (8517513).

Almost surely, 2^28391705 is an apocalyptic number.

It is an amenable number.

28391705 is a deficient number, since it is larger than the sum of its proper divisors (5678347).

28391705 is an equidigital number, since it uses as much as digits as its factorization.

28391705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5678346.

The product of its (nonzero) digits is 15120, while the sum is 35.

The square root of 28391705 is about 5328.3867164462. The cubic root of 28391705 is about 305.0683533983.

The spelling of 28391705 in words is "twenty-eight million, three hundred ninety-one thousand, seven hundred five".