181805 has 8 divisors (see below), whose sum is σ = 235032. Its totient is φ = 134208.

The previous prime is 181789. The next prime is 181813. The reversal of 181805 is 508181.

181805 = 301² + 302².

181805 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 11236 + 170569 = 106^2 + 413^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 181805 - 2⁴ = 181789 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 7 ways as a sum of consecutive naturals, for example, 1334 + ... + 1463.

It is an arithmetic number, because the mean of its divisors is an integer number (29379).

2¹⁸¹⁸⁰⁵ is an apocalyptic number.

181805 is the 302-nd centered square number.

It is an amenable number.

181805 is a deficient number, since it is larger than the sum of its proper divisors (53227).

181805 is a wasteful number, since it uses less digits than its factorization.

181805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2815.

The product of its (nonzero) digits is 320, while the sum is 23.

The square root of 181805 is about 426.3859753791. The cubic root of 181805 is about 56.6502643800.

Adding to 181805 its reverse (508181), we get a palindrome (689986).

The spelling of 181805 in words is "one hundred eighty-one thousand, eight hundred five".