181945 has 4 divisors (see below), whose sum is σ = 218340. Its totient is φ = 145552.

The previous prime is 181943. The next prime is 181957. The reversal of 181945 is 549181.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 549181 = 233 ⋅2357.

It can be written as a sum of positive squares in 2 ways, for example, as 131769 + 50176 = 363^2 + 224^2 .

It is a cyclic number.

It is not a de Polignac number, because 181945 - 2¹ = 181943 is a prime.

It is not an unprimeable number, because it can be changed into a prime (181943) 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, 18190 + ... + 18199.

It is an arithmetic number, because the mean of its divisors is an integer number (54585).

2¹⁸¹⁹⁴⁵ is an apocalyptic number.

It is an amenable number.

181945 is a deficient number, since it is larger than the sum of its proper divisors (36395).

181945 is an equidigital number, since it uses as much as digits as its factorization.

181945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36394.

The product of its digits is 1440, while the sum is 28.

The square root of 181945 is about 426.5501142890. The cubic root of 181945 is about 56.6648019379.

Subtracting 181945 from its reverse (549181), we obtain a square (367236 = 606²).

The spelling of 181945 in words is "one hundred eighty-one thousand, nine hundred forty-five".