166661 has 8 divisors (see below), whose sum is σ = 184800. Its totient is φ = 149040.

The previous prime is 166657. The next prime is 166667.

166661 = 14² + 15² + ... + 79².

166661 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 166661 - 2² = 166657 is a prime.

It is an Ulam number.

It is a Curzon number.

It is a plaindrome in base 15.

It is a self number, because there is not a number n which added to its sum of digits gives 166661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (166667) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1130 + ... + 1268.

It is an arithmetic number, because the mean of its divisors is an integer number (23100).

2¹⁶⁶⁶⁶¹ is an apocalyptic number.

166661 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

166661 is a deficient number, since it is larger than the sum of its proper divisors (18139).

166661 is a wasteful number, since it uses less digits than its factorization.

166661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 259.

The product of its digits is 1296, while the sum is 26.

The square root of 166661 is about 408.2413501839. The cubic root of 166661 is about 55.0314971105.

The spelling of 166661 in words is "one hundred sixty-six thousand, six hundred sixty-one".