66181 has 6 divisors (see below), whose sum is σ = 70610. Its totient is φ = 62016.

The previous prime is 66179. The next prime is 66191. The reversal of 66181 is 18166.

It can be written as a sum of positive squares in 3 ways, for example, as 43681 + 22500 = 209^2 + 150^2 .

It is not a de Polignac number, because 66181 - 2¹ = 66179 is a prime.

It is a super-2 number, since 2×66181² = 8759849522, 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 (66161) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 175 + ... + 403.

2⁶⁶¹⁸¹ is an apocalyptic number.

It is an amenable number.

66181 is a deficient number, since it is larger than the sum of its proper divisors (4429).

66181 is a wasteful number, since it uses less digits than its factorization.

66181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263 (or 246 counting only the distinct ones).

The product of its digits is 288, while the sum is 22.

The square root of 66181 is about 257.2566811572. The cubic root of 66181 is about 40.4493091354.

The spelling of 66181 in words is "sixty-six thousand, one hundred eighty-one".