166639 has 4 divisors (see below), whose sum is σ = 181800. Its totient is φ = 151480.

The previous prime is 166631. The next prime is 166643. The reversal of 166639 is 936661.

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

It is a cyclic number.

It is not a de Polignac number, because 166639 - 2³ = 166631 is a prime.

It is a Duffinian number.

166639 is a lucky number.

It is a plaindrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 166639.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166631) 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, 7564 + ... + 7585.

It is an arithmetic number, because the mean of its divisors is an integer number (45450).

2¹⁶⁶⁶³⁹ is an apocalyptic number.

166639 is a deficient number, since it is larger than the sum of its proper divisors (15161).

166639 is a wasteful number, since it uses less digits than its factorization.

166639 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15160.

The product of its digits is 5832, while the sum is 31.

The square root of 166639 is about 408.2144044494. The cubic root of 166639 is about 55.0290755357.

The spelling of 166639 in words is "one hundred sixty-six thousand, six hundred thirty-nine".