181381 has 4 divisors (see below), whose sum is σ = 187264. Its totient is φ = 175500.

The previous prime is 181361. The next prime is 181387. The reversal of 181381 is 183181.

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: 183181 = 83 ⋅2207.

It is a cyclic number.

It is not a de Polignac number, because 181381 - 2⁷ = 181253 is a prime.

It is a super-2 number, since 2×181381² = 65798134322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

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, 2895 + ... + 2956.

It is an arithmetic number, because the mean of its divisors is an integer number (46816).

2¹⁸¹³⁸¹ is an apocalyptic number.

It is an amenable number.

181381 is a deficient number, since it is larger than the sum of its proper divisors (5883).

181381 is an equidigital number, since it uses as much as digits as its factorization.

181381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5882.

The product of its digits is 192, while the sum is 22.

The square root of 181381 is about 425.8884830563. Note that the first 3 decimals coincide. The cubic root of 181381 is about 56.6061907682.

The spelling of 181381 in words is "one hundred eighty-one thousand, three hundred eighty-one".