28108709 has 4 divisors (see below), whose sum is σ = 28639116. Its totient is φ = 27578304.

The previous prime is 28108673. The next prime is 28108777. The reversal of 28108709 is 90780182.

It is a happy number.

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 21883684 + 6225025 = 4678^2 + 2495^2 .

It is a cyclic number.

It is not a de Polignac number, because 28108709 - 2¹² = 28104613 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28108109) 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, 265124 + ... + 265229.

It is an arithmetic number, because the mean of its divisors is an integer number (7159779).

Almost surely, 2^28108709 is an apocalyptic number.

It is an amenable number.

28108709 is a deficient number, since it is larger than the sum of its proper divisors (530407).

28108709 is an equidigital number, since it uses as much as digits as its factorization.

28108709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 530406.

The product of its (nonzero) digits is 8064, while the sum is 35.

The square root of 28108709 is about 5301.7647062087. The cubic root of 28108709 is about 304.0513713105.

The spelling of 28108709 in words is "twenty-eight million, one hundred eight thousand, seven hundred nine".