218851 has 4 divisors (see below), whose sum is σ = 221400. Its totient is φ = 216304.

The previous prime is 218849. The next prime is 218857. The reversal of 218851 is 158812.

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

It is a cyclic number.

It is not a de Polignac number, because 218851 - 2¹ = 218849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218857) 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 3 ways as a sum of consecutive naturals, for example, 1141 + ... + 1318.

It is an arithmetic number, because the mean of its divisors is an integer number (55350).

2²¹⁸⁸⁵¹ is an apocalyptic number.

218851 is a deficient number, since it is larger than the sum of its proper divisors (2549).

218851 is an equidigital number, since it uses as much as digits as its factorization.

218851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2548.

The product of its digits is 640, while the sum is 25.

The square root of 218851 is about 467.8151344281. The cubic root of 218851 is about 60.2628284868.

The spelling of 218851 in words is "two hundred eighteen thousand, eight hundred fifty-one".