166009 has 4 divisors (see below), whose sum is σ = 170100. Its totient is φ = 161920.

The previous prime is 165983. The next prime is 166013. The reversal of 166009 is 900661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 900661 = 47 ⋅19163.

It can be written as a sum of positive squares in 2 ways, for example, as 21609 + 144400 = 147^2 + 380^2 .

It is a cyclic number.

It is not a de Polignac number, because 166009 - 2¹⁵ = 133241 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166099) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1984 + ... + 2065.

It is an arithmetic number, because the mean of its divisors is an integer number (42525).

2¹⁶⁶⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

166009 is a deficient number, since it is larger than the sum of its proper divisors (4091).

166009 is an equidigital number, since it uses as much as digits as its factorization.

166009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4090.

The product of its (nonzero) digits is 324, while the sum is 22.

The square root of 166009 is about 407.4420204152. The cubic root of 166009 is about 54.9596398116.

The spelling of 166009 in words is "one hundred sixty-six thousand, nine".