166181 has 4 divisors (see below), whose sum is σ = 167532. Its totient is φ = 164832.

The previous prime is 166169. The next prime is 166183. The reversal of 166181 is 181661.

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: 181661 = 59 ⋅3079.

It can be written as a sum of positive squares in 2 ways, for example, as 43681 + 122500 = 209^2 + 350^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166181 is a prime.

It is a super-2 number, since 2×166181² = 55232249522, 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 (166183) 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, 470 + ... + 743.

It is an arithmetic number, because the mean of its divisors is an integer number (41883).

2¹⁶⁶¹⁸¹ is an apocalyptic number.

It is an amenable number.

166181 is a deficient number, since it is larger than the sum of its proper divisors (1351).

166181 is a wasteful number, since it uses less digits than its factorization.

166181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1350.

The product of its digits is 288, while the sum is 23.

The square root of 166181 is about 407.6530387474. The cubic root of 166181 is about 54.9786142752.

The spelling of 166181 in words is "one hundred sixty-six thousand, one hundred eighty-one".