216816 has 20 divisors (see below), whose sum is σ = 560232. Its totient is φ = 72256.

The previous prime is 216803. The next prime is 216829. The reversal of 216816 is 618612.

It is an interprime number because it is at equal distance from previous prime (216803) and next prime (216829).

It is a Harshad number since it is a multiple of its sum of digits (24).

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

It is a congruent number.

It is an unprimeable number.

216816 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2211 + ... + 2306.

2²¹⁶⁸¹⁶ is an apocalyptic number.

It is an amenable number.

216816 is an abundant number, since it is smaller than the sum of its proper divisors (343416).

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

216816 is a wasteful number, since it uses less digits than its factorization.

216816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4528 (or 4522 counting only the distinct ones).

The product of its digits is 576, while the sum is 24.

The square root of 216816 is about 465.6350502271. The cubic root of 216816 is about 60.0754606107.

The spelling of 216816 in words is "two hundred sixteen thousand, eight hundred sixteen".