128181 has 4 divisors (see below), whose sum is σ = 170912. Its totient is φ = 85452.

The previous prime is 128173. The next prime is 128189. The reversal of 128181 is 181821.

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: 181821 = 3 ⋅60607.

It is an interprime number because it is at equal distance from previous prime (128173) and next prime (128189).

It is not a de Polignac number, because 128181 - 2³ = 128173 is a prime.

It is a super-2 number, since 2×128181² = 32860737522, which contains 22 as substring.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 128181.

It is not an unprimeable number, because it can be changed into a prime (128189) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21361 + ... + 21366.

It is an arithmetic number, because the mean of its divisors is an integer number (42728).

2¹²⁸¹⁸¹ is an apocalyptic number.

It is an amenable number.

128181 is a deficient number, since it is larger than the sum of its proper divisors (42731).

128181 is an equidigital number, since it uses as much as digits as its factorization.

128181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 42730.

The product of its digits is 128, while the sum is 21.

The square root of 128181 is about 358.0237422295. The cubic root of 128181 is about 50.4205855691.

It can be divided in two parts, 1 and 28181, that added together give a palindrome (28182).

The spelling of 128181 in words is "one hundred twenty-eight thousand, one hundred eighty-one".