218605 has 4 divisors (see below), whose sum is σ = 262332. Its totient is φ = 174880.

The previous prime is 218599. The next prime is 218611. The reversal of 218605 is 506812.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (218599) and next prime (218611).

It can be written as a sum of positive squares in 2 ways, for example, as 114921 + 103684 = 339^2 + 322^2 .

It is a de Polignac number, because none of the positive numbers 2^k-218605 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a nialpdrome in base 12.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 21856 + ... + 21865.

It is an arithmetic number, because the mean of its divisors is an integer number (65583).

2²¹⁸⁶⁰⁵ is an apocalyptic number.

It is an amenable number.

218605 is a deficient number, since it is larger than the sum of its proper divisors (43727).

218605 is an equidigital number, since it uses as much as digits as its factorization.

218605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 43726.

The product of its (nonzero) digits is 480, while the sum is 22.

The square root of 218605 is about 467.5521361303. The cubic root of 218605 is about 60.2402404949.

The spelling of 218605 in words is "two hundred eighteen thousand, six hundred five".