156809 has 4 divisors (see below), whose sum is σ = 157716. Its totient is φ = 155904.

The previous prime is 156799. The next prime is 156817. The reversal of 156809 is 908651.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 908651 = 47 ⋅19333.

It can be written as a sum of positive squares in 2 ways, for example, as 41209 + 115600 = 203^2 + 340^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-156809 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 (156899) 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 in 3 ways as a sum of consecutive naturals, for example, 104 + ... + 569.

It is an arithmetic number, because the mean of its divisors is an integer number (39429).

2¹⁵⁶⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

156809 is a deficient number, since it is larger than the sum of its proper divisors (907).

156809 is an equidigital number, since it uses as much as digits as its factorization.

156809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 906.

The product of its (nonzero) digits is 2160, while the sum is 29.

The square root of 156809 is about 395.9911615175. The cubic root of 156809 is about 53.9250216848.

The spelling of 156809 in words is "one hundred fifty-six thousand, eight hundred nine".