166591 has 4 divisors (see below), whose sum is σ = 169384. Its totient is φ = 163800.

The previous prime is 166571. The next prime is 166597. The reversal of 166591 is 195661.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-166591 is a prime.

It is a super-2 number, since 2×166591² = 55505122562, which contains 22 as substring.

It is a Duffinian number.

It is a plaindrome in base 16.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166597) 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, 1305 + ... + 1426.

It is an arithmetic number, because the mean of its divisors is an integer number (42346).

2¹⁶⁶⁵⁹¹ is an apocalyptic number.

166591 is a deficient number, since it is larger than the sum of its proper divisors (2793).

166591 is an equidigital number, since it uses as much as digits as its factorization.

166591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2792.

The product of its digits is 1620, while the sum is 28.

The square root of 166591 is about 408.1556075812. The cubic root of 166591 is about 55.0237913600.

It can be divided in two parts, 166 and 591, that added together give a palindrome (757).

The spelling of 166591 in words is "one hundred sixty-six thousand, five hundred ninety-one".