166444181 has 4 divisors (see below), whose sum is σ = 166470252. Its totient is φ = 166418112.

The previous prime is 166444121. The next prime is 166444183. The reversal of 166444181 is 181444661.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 181444661 = 19 ⋅9549719.

It can be written as a sum of positive squares in 2 ways, for example, as 122434225 + 44009956 = 11065^2 + 6634^2 .

It is a cyclic number.

It is not a de Polignac number, because 166444181 - 2¹⁴ = 166427797 is a prime.

It is a super-3 number, since 3×166444181³ (a number of 26 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166444183) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3725 + ... + 18621.

It is an arithmetic number, because the mean of its divisors is an integer number (41617563).

It is a Poulet number, since it divides 2^166444180-1.

Almost surely, 2^166444181 is an apocalyptic number.

It is an amenable number.

166444181 is a deficient number, since it is larger than the sum of its proper divisors (26071).

166444181 is a wasteful number, since it uses less digits than its factorization.

166444181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26070.

The product of its digits is 18432, while the sum is 35.

The square root of 166444181 is about 12901.3247769367. The cubic root of 166444181 is about 550.0762219432.

The spelling of 166444181 in words is "one hundred sixty-six million, four hundred forty-four thousand, one hundred eighty-one".