166091 has 4 divisors (see below), whose sum is σ = 170184. Its totient is φ = 162000.

The previous prime is 166081. The next prime is 166099. The reversal of 166091 is 190661.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 190661 = 37 ⋅5153.

It is a cyclic number.

It is not a de Polignac number, because 166091 - 2⁶ = 166027 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 166091.

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, 1985 + ... + 2066.

It is an arithmetic number, because the mean of its divisors is an integer number (42546).

2¹⁶⁶⁰⁹¹ is an apocalyptic number.

166091 is a deficient number, since it is larger than the sum of its proper divisors (4093).

166091 is an equidigital number, since it uses as much as digits as its factorization.

166091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4092.

The product of its (nonzero) digits is 324, while the sum is 23.

The square root of 166091 is about 407.5426358064. The cubic root of 166091 is about 54.9686874107.

The spelling of 166091 in words is "one hundred sixty-six thousand, ninety-one".