216321 has 8 divisors (see below), whose sum is σ = 329664. Its totient is φ = 123600.

The previous prime is 216319. The next prime is 216329. The reversal of 216321 is 123612.

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

It is not a de Polignac number, because 216321 - 2¹ = 216319 is a prime.

It is a Smith number, since the sum of its digits (15) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is an alternating number because its digits alternate between even and odd.

It is a self number, because there is not a number n which added to its sum of digits gives 216321.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 216321.

It is not an unprimeable number, because it can be changed into a prime (216329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5130 + ... + 5171.

It is an arithmetic number, because the mean of its divisors is an integer number (41208).

2²¹⁶³²¹ is an apocalyptic number.

216321 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

216321 is a deficient number, since it is larger than the sum of its proper divisors (113343).

216321 is a wasteful number, since it uses less digits than its factorization.

216321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10311.

The product of its digits is 72, while the sum is 15.

The square root of 216321 is about 465.1032143514. The cubic root of 216321 is about 60.0297075109.

Adding to 216321 its reverse (123612), we get a palindrome (339933).

The spelling of 216321 in words is "two hundred sixteen thousand, three hundred twenty-one".