213666 has 16 divisors (see below), whose sum is σ = 432000. Its totient is φ = 70448.

The previous prime is 213659. The next prime is 213713. The reversal of 213666 is 666312.

213666 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a nude number because it is divisible by every one of its digits.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 213666.

It is an unprimeable number.

213666 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 775 + ... + 1013.

It is an arithmetic number, because the mean of its divisors is an integer number (27000).

2²¹³⁶⁶⁶ is an apocalyptic number.

213666 is an abundant number, since it is smaller than the sum of its proper divisors (218334).

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

213666 is a wasteful number, since it uses less digits than its factorization.

213666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 393.

The product of its digits is 1296, while the sum is 24.

The square root of 213666 is about 462.2401973001. The cubic root of 213666 is about 59.7831057819.

Adding to 213666 its reverse (666312), we get a palindrome (879978).

The spelling of 213666 in words is "two hundred thirteen thousand, six hundred sixty-six".