16666 has 8 divisors (see below), whose sum is σ = 26964. Its totient is φ = 7680.

The previous prime is 16661. The next prime is 16673. The reversal of 16666 is 66661.

16666 = T₄₄ + T₄₅ + ... + T₅₆.

It can be written as a sum of positive squares in 2 ways, for example, as 16641 + 25 = 129^2 + 5^2 .

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

16666 is a modest number, since divided by 666 gives 16 as remainder.

It is a plaindrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 16666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16661) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 295 + ... + 346.

2¹⁶⁶⁶⁶ is an apocalyptic number.

16666 is a deficient number, since it is larger than the sum of its proper divisors (10298).

16666 is a wasteful number, since it uses less digits than its factorization.

16666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 656.

The product of its digits is 1296, while the sum is 25.

The square root of 16666 is about 129.0968628589. The cubic root of 16666 is about 25.5433071599.

Subtracting from 16666 its sum of digits (25), we obtain a square (16641 = 129²).

It can be divided in two parts, 166 and 66, that added together give a palindrome (232).

The spelling of 16666 in words is "sixteen thousand, six hundred sixty-six".