218505 has 16 divisors (see below), whose sum is σ = 399744. Its totient is φ = 99840.

The previous prime is 218479. The next prime is 218509. The reversal of 218505 is 505812.

218505 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 218505 - 2⁸ = 218249 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is an alternating number because its digits alternate between even and odd.

It is a Curzon number.

218505 is a lucky number.

It is a plaindrome in base 16.

It is not an unprimeable number, because it can be changed into a prime (218509) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 936 + ... + 1145.

It is an arithmetic number, because the mean of its divisors is an integer number (24984).

2²¹⁸⁵⁰⁵ is an apocalyptic number.

It is an amenable number.

218505 is a deficient number, since it is larger than the sum of its proper divisors (181239).

218505 is a wasteful number, since it uses less digits than its factorization.

218505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2096.

The product of its (nonzero) digits is 400, while the sum is 21.

The square root of 218505 is about 467.4451839521. The cubic root of 218505 is about 60.2310535400.

The spelling of 218505 in words is "two hundred eighteen thousand, five hundred five".