218217 has 4 divisors (see below), whose sum is σ = 290960. Its totient is φ = 145476.

The previous prime is 218213. The next prime is 218227. The reversal of 218217 is 712812.

218217 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 218217 - 2² = 218213 is a prime.

It is a D-number.

It is a Duffinian number.

218217 is a lucky number.

It is a plaindrome in base 15.

It is a junction number, because it is equal to n+sod(n) for n = 218193 and 218202.

It is not an unprimeable number, because it can be changed into a prime (218213) 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, 36367 + ... + 36372.

It is an arithmetic number, because the mean of its divisors is an integer number (72740).

2²¹⁸²¹⁷ is an apocalyptic number.

It is an amenable number.

218217 is a deficient number, since it is larger than the sum of its proper divisors (72743).

218217 is an equidigital number, since it uses as much as digits as its factorization.

218217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72742.

The product of its digits is 224, while the sum is 21.

The square root of 218217 is about 467.1370248653. The cubic root of 218217 is about 60.2045794392.

It can be divided in two parts, 218 and 217, that added together give a triangular number (435 = T₂₉).

The spelling of 218217 in words is "two hundred eighteen thousand, two hundred seventeen".