181309 has 4 divisors (see below), whose sum is σ = 189216. Its totient is φ = 173404.

The previous prime is 181303. The next prime is 181361. The reversal of 181309 is 903181.

181309 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 903181 = 239 ⋅3779.

It is a cyclic number.

It is not a de Polignac number, because 181309 - 2³ = 181301 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 181309.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (181301) 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, 3919 + ... + 3964.

It is an arithmetic number, because the mean of its divisors is an integer number (47304).

2¹⁸¹³⁰⁹ is an apocalyptic number.

It is an amenable number.

181309 is a deficient number, since it is larger than the sum of its proper divisors (7907).

181309 is an equidigital number, since it uses as much as digits as its factorization.

181309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7906.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 181309 is about 425.8039454960. The cubic root of 181309 is about 56.5986997500.

The spelling of 181309 in words is "one hundred eighty-one thousand, three hundred nine".