28240705 has 4 divisors (see below), whose sum is σ = 33888852. Its totient is φ = 22592560.

The previous prime is 28240703. The next prime is 28240717. The reversal of 28240705 is 50704282.

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 4260096 + 23980609 = 2064^2 + 4897^2 .

It is not a de Polignac number, because 28240705 - 2¹ = 28240703 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28240703) 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, 2824066 + ... + 2824075.

It is an arithmetic number, because the mean of its divisors is an integer number (8472213).

Almost surely, 2^28240705 is an apocalyptic number.

It is an amenable number.

28240705 is a deficient number, since it is larger than the sum of its proper divisors (5648147).

28240705 is an equidigital number, since it uses as much as digits as its factorization.

28240705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5648146.

The product of its (nonzero) digits is 4480, while the sum is 28.

The square root of 28240705 is about 5314.1984343831. The cubic root of 28240705 is about 304.5265610102.

Adding to 28240705 its reverse (50704282), we get a palindrome (78944987).

The spelling of 28240705 in words is "twenty-eight million, two hundred forty thousand, seven hundred five".