216685 has 16 divisors (see below), whose sum is σ = 306432. Its totient is φ = 144000.

The previous prime is 216679. The next prime is 216703. The reversal of 216685 is 586612.

It is not a de Polignac number, because 216685 - 2⁵ = 216653 is a prime.

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 in 15 ways as a sum of consecutive naturals, for example, 1360 + ... + 1510.

It is an arithmetic number, because the mean of its divisors is an integer number (19152).

2²¹⁶⁶⁸⁵ is an apocalyptic number.

It is an amenable number.

216685 is a deficient number, since it is larger than the sum of its proper divisors (89747).

216685 is a wasteful number, since it uses less digits than its factorization.

216685 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 204.

The product of its digits is 2880, while the sum is 28.

The square root of 216685 is about 465.4943608681. The cubic root of 216685 is about 60.0633589963.

The spelling of 216685 in words is "two hundred sixteen thousand, six hundred eighty-five".