181385 has 4 divisors (see below), whose sum is σ = 217668. Its totient is φ = 145104.

The previous prime is 181361. The next prime is 181387. The reversal of 181385 is 583181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 109561 + 71824 = 331^2 + 268^2 .

It is a cyclic number.

It is not a de Polignac number, because 181385 - 2¹⁰ = 180361 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a nialpdrome in base 8.

It is not an unprimeable number, because it can be changed into a prime (181387) 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, 18134 + ... + 18143.

It is an arithmetic number, because the mean of its divisors is an integer number (54417).

2¹⁸¹³⁸⁵ is an apocalyptic number.

It is an amenable number.

181385 is a deficient number, since it is larger than the sum of its proper divisors (36283).

181385 is an equidigital number, since it uses as much as digits as its factorization.

181385 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 36282.

The product of its digits is 960, while the sum is 26.

The square root of 181385 is about 425.8931790954. The cubic root of 181385 is about 56.6066068777.

The spelling of 181385 in words is "one hundred eighty-one thousand, three hundred eighty-five".