181865 has 4 divisors (see below), whose sum is σ = 218244. Its totient is φ = 145488.

The previous prime is 181837. The next prime is 181871. The reversal of 181865 is 568181.

181865 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 an emirpimes, since its reverse is a distinct semiprime: 568181 = 227 ⋅2503.

It can be written as a sum of positive squares in 2 ways, for example, as 94249 + 87616 = 307^2 + 296^2 .

It is a cyclic number.

It is not a de Polignac number, because 181865 - 2⁸ = 181609 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18182 + ... + 18191.

It is an arithmetic number, because the mean of its divisors is an integer number (54561).

2¹⁸¹⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

181865 is a deficient number, since it is larger than the sum of its proper divisors (36379).

181865 is an equidigital number, since it uses as much as digits as its factorization.

181865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36378.

The product of its digits is 1920, while the sum is 29.

The square root of 181865 is about 426.4563283620. The cubic root of 181865 is about 56.6564956755.

The spelling of 181865 in words is "one hundred eighty-one thousand, eight hundred sixty-five".