135809 has 4 divisors (see below), whose sum is σ = 137904. Its totient is φ = 133716.

The previous prime is 135799. The next prime is 135829. The reversal of 135809 is 908531.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 135809 - 2¹² = 131713 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (135829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 947 + ... + 1080.

It is an arithmetic number, because the mean of its divisors is an integer number (34476).

2¹³⁵⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

135809 is a deficient number, since it is larger than the sum of its proper divisors (2095).

135809 is an equidigital number, since it uses as much as digits as its factorization.

135809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2094.

The product of its (nonzero) digits is 1080, while the sum is 26.

The square root of 135809 is about 368.5227265719. The cubic root of 135809 is about 51.4015462802.

The spelling of 135809 in words is "one hundred thirty-five thousand, eight hundred nine".