216813 has 4 divisors (see below), whose sum is σ = 289088. Its totient is φ = 144540.

The previous prime is 216803. The next prime is 216829. The reversal of 216813 is 318612.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 216813 - 2⁵ = 216781 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a plaindrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 216813.

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 polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36133 + ... + 36138.

It is an arithmetic number, because the mean of its divisors is an integer number (72272).

2²¹⁶⁸¹³ is an apocalyptic number.

It is an amenable number.

216813 is a deficient number, since it is larger than the sum of its proper divisors (72275).

216813 is an equidigital number, since it uses as much as digits as its factorization.

216813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72274.

The product of its digits is 288, while the sum is 21.

The square root of 216813 is about 465.6318288090. The cubic root of 216813 is about 60.0751835290.

The spelling of 216813 in words is "two hundred sixteen thousand, eight hundred thirteen".