27809 has 2 divisors, whose sum is σ = 27810. Its totient is φ = 27808.

The previous prime is 27803. The next prime is 27817. The reversal of 27809 is 90872.

27809 is nontrivially palindromic in base 11.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25600 + 2209 = 160^2 + 47^2 .

It is a cyclic number.

It is not a de Polignac number, because 27809 - 2⁴ = 27793 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a nialpdrome in base 13.

It is not a weakly prime, because it can be changed into another prime (27803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 13904 + 13905.

It is an arithmetic number, because the mean of its divisors is an integer number (13905).

2²⁷⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

27809 is a deficient number, since it is larger than the sum of its proper divisors (1).

27809 is an equidigital number, since it uses as much as digits as its factorization.

27809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 26.

The square root of 27809 is about 166.7603070278. The cubic root of 27809 is about 30.2966858738.

The spelling of 27809 in words is "twenty-seven thousand, eight hundred nine".