218221 has 4 divisors (see below), whose sum is σ = 222912. Its totient is φ = 213532.

The previous prime is 218213. The next prime is 218227. The reversal of 218221 is 122812.

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 a cyclic number.

It is not a de Polignac number, because 218221 - 2³ = 218213 is a prime.

It is a Duffinian number.

218221 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 218195 and 218204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218227) 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, 2275 + ... + 2368.

It is an arithmetic number, because the mean of its divisors is an integer number (55728).

2²¹⁸²²¹ is an apocalyptic number.

It is an amenable number.

218221 is a deficient number, since it is larger than the sum of its proper divisors (4691).

218221 is an equidigital number, since it uses as much as digits as its factorization.

218221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4690.

The product of its digits is 64, while the sum is 16.

The square root of 218221 is about 467.1413062447. The cubic root of 218221 is about 60.2049472945.

The spelling of 218221 in words is "two hundred eighteen thousand, two hundred twenty-one".