16668 has 18 divisors (see below), whose sum is σ = 42224. Its totient is φ = 5544.

The previous prime is 16661. The next prime is 16673. The reversal of 16668 is 86661.

It is a tau number, because it is divible by the number of its divisors (18).

It is a plaindrome in base 10.

It is a nialpdrome in base 7.

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 5 ways as a sum of consecutive naturals, for example, 196 + ... + 267.

2¹⁶⁶⁶⁸ is an apocalyptic number.

16668 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

16668 is an abundant number, since it is smaller than the sum of its proper divisors (25556).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

16668 is a wasteful number, since it uses less digits than its factorization.

16668 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 473 (or 468 counting only the distinct ones).

The product of its digits is 1728, while the sum is 27.

The square root of 16668 is about 129.1046087481. The cubic root of 16668 is about 25.5443288922.

Subtracting from 16668 its sum of digits (27), we obtain a square (16641 = 129²).

The spelling of 16668 in words is "sixteen thousand, six hundred sixty-eight".