28717609 has 4 divisors (see below), whose sum is σ = 28799316. Its totient is φ = 28635904.

The previous prime is 28717597. The next prime is 28717613. The reversal of 28717609 is 90671782.

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 17347225 + 11370384 = 4165^2 + 3372^2 .

It is a cyclic number.

It is not a de Polignac number, because 28717609 - 2²¹ = 26620457 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28717649) 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, 40324 + ... + 41029.

It is an arithmetic number, because the mean of its divisors is an integer number (7199829).

Almost surely, 2^28717609 is an apocalyptic number.

It is an amenable number.

28717609 is a deficient number, since it is larger than the sum of its proper divisors (81707).

28717609 is an equidigital number, since it uses as much as digits as its factorization.

28717609 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81706.

The product of its (nonzero) digits is 42336, while the sum is 40.

The square root of 28717609 is about 5358.8813198279. The cubic root of 28717609 is about 306.2311928476.

The spelling of 28717609 in words is "twenty-eight million, seven hundred seventeen thousand, six hundred nine".