218866 has 4 divisors (see below), whose sum is σ = 328302. Its totient is φ = 109432.

The previous prime is 218857. The next prime is 218873. The reversal of 218866 is 668812.

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

It can be written as a sum of positive squares in only one way, i.e., 137641 + 81225 = 371^2 + 285^2 .

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 54715 + ... + 54718.

2²¹⁸⁸⁶⁶ is an apocalyptic number.

218866 is a deficient number, since it is larger than the sum of its proper divisors (109436).

218866 is a wasteful number, since it uses less digits than its factorization.

218866 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109435.

The product of its digits is 4608, while the sum is 31.

The square root of 218866 is about 467.8311661273. The cubic root of 218866 is about 60.2642052558.

The spelling of 218866 in words is "two hundred eighteen thousand, eight hundred sixty-six".