166891 has 4 divisors (see below), whose sum is σ = 168112. Its totient is φ = 165672.

The previous prime is 166871. The next prime is 166909. The reversal of 166891 is 198661.

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: 198661 = 257 ⋅773.

It is a cyclic number.

It is not a de Polignac number, because 166891 - 2¹³ = 158699 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (166841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 375 + ... + 688.

It is an arithmetic number, because the mean of its divisors is an integer number (42028).

2¹⁶⁶⁸⁹¹ is an apocalyptic number.

166891 is a deficient number, since it is larger than the sum of its proper divisors (1221).

166891 is a wasteful number, since it uses less digits than its factorization.

166891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1220.

The product of its digits is 2592, while the sum is 31.

The square root of 166891 is about 408.5229491718. The cubic root of 166891 is about 55.0568008233.

The spelling of 166891 in words is "one hundred sixty-six thousand, eight hundred ninety-one".