216805 has 8 divisors (see below), whose sum is σ = 262944. Its totient is φ = 171600.

The previous prime is 216803. The next prime is 216829. The reversal of 216805 is 508612.

It is a happy number.

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

It is not a de Polignac number, because 216805 - 2¹ = 216803 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216803) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 490 + ... + 820.

It is an arithmetic number, because the mean of its divisors is an integer number (32868).

2²¹⁶⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

216805 is a deficient number, since it is larger than the sum of its proper divisors (46139).

216805 is a wasteful number, since it uses less digits than its factorization.

216805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 467.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 216805 is about 465.6232382517. The cubic root of 216805 is about 60.0744446321.

It can be divided in two parts, 2 and 16805, that added together give a 5-th power (16807 = 7⁵).

The spelling of 216805 in words is "two hundred sixteen thousand, eight hundred five".