218805 has 16 divisors (see below), whose sum is σ = 362880. Its totient is φ = 112448.

The previous prime is 218797. The next prime is 218809. The reversal of 218805 is 508812.

It is a cyclic number.

It is not a de Polignac number, because 218805 - 2³ = 218797 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 218805.

It is not an unprimeable number, because it can be changed into a prime (218809) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 184 + ... + 686.

It is an arithmetic number, because the mean of its divisors is an integer number (22680).

2²¹⁸⁸⁰⁵ is an apocalyptic number.

It is an amenable number.

218805 is a deficient number, since it is larger than the sum of its proper divisors (144075).

218805 is a wasteful number, since it uses less digits than its factorization.

218805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 540.

The product of its (nonzero) digits is 640, while the sum is 24.

The square root of 218805 is about 467.7659671246. The cubic root of 218805 is about 60.2586060031.

The spelling of 218805 in words is "two hundred eighteen thousand, eight hundred five".