28113209 has 4 divisors (see below), whose sum is σ = 29082660. Its totient is φ = 27143760.

The previous prime is 28113193. The next prime is 28113221. The reversal of 28113209 is 90231182.

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 11751184 + 16362025 = 3428^2 + 4045^2 .

It is a cyclic number.

It is not a de Polignac number, because 28113209 - 2⁴ = 28113193 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28113259) 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, 484682 + ... + 484739.

It is an arithmetic number, because the mean of its divisors is an integer number (7270665).

Almost surely, 2^28113209 is an apocalyptic number.

28113209 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

28113209 is a deficient number, since it is larger than the sum of its proper divisors (969451).

28113209 is an equidigital number, since it uses as much as digits as its factorization.

28113209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 969450.

The product of its (nonzero) digits is 864, while the sum is 26.

The square root of 28113209 is about 5302.1890762213. The cubic root of 28113209 is about 304.0675959162.

The spelling of 28113209 in words is "twenty-eight million, one hundred thirteen thousand, two hundred nine".