216686 has 4 divisors (see below), whose sum is σ = 325032. Its totient is φ = 108342.

The previous prime is 216679. The next prime is 216703. The reversal of 216686 is 686612.

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

It is a Curzon number.

It is a plaindrome in base 11.

It is a congruent number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 54170 + ... + 54173.

It is an arithmetic number, because the mean of its divisors is an integer number (81258).

2²¹⁶⁶⁸⁶ is an apocalyptic number.

216686 is a deficient number, since it is larger than the sum of its proper divisors (108346).

216686 is a wasteful number, since it uses less digits than its factorization.

216686 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 108345.

The product of its digits is 3456, while the sum is 29.

The square root of 216686 is about 465.4954349937. The cubic root of 216686 is about 60.0634513935.

The spelling of 216686 in words is "two hundred sixteen thousand, six hundred eighty-six".