216823 has 4 divisors (see below), whose sum is σ = 220968. Its totient is φ = 212680.

The previous prime is 216803. The next prime is 216829. The reversal of 216823 is 328612.

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

It is a cyclic number.

It is not a de Polignac number, because 216823 - 2⁵ = 216791 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 216794 and 216803.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (216829) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1993 + ... + 2098.

It is an arithmetic number, because the mean of its divisors is an integer number (55242).

2²¹⁶⁸²³ is an apocalyptic number.

216823 is a deficient number, since it is larger than the sum of its proper divisors (4145).

216823 is an equidigital number, since it uses as much as digits as its factorization.

216823 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4144.

The product of its digits is 576, while the sum is 22.

The square root of 216823 is about 465.6425667827. The cubic root of 216823 is about 60.0761071246.

The spelling of 216823 in words is "two hundred sixteen thousand, eight hundred twenty-three".