218666844 has 144 divisors (see below), whose sum is σ = 645741600. Its totient is φ = 63866880.

The previous prime is 218666821. The next prime is 218666849. The reversal of 218666844 is 448666812.

It is a self number, because there is not a number n which added to its sum of digits gives 218666844.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218666849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 378684 + ... + 379260.

Almost surely, 2^218666844 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 218666844, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (322870800).

218666844 is an abundant number, since it is smaller than the sum of its proper divisors (427074756).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

218666844 is a wasteful number, since it uses less digits than its factorization.

218666844 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 641 (or 622 counting only the distinct ones).

The product of its digits is 442368, while the sum is 45.

The square root of 218666844 is about 14787.3880046477. The cubic root of 218666844 is about 602.4592067329.

The spelling of 218666844 in words is "two hundred eighteen million, six hundred sixty-six thousand, eight hundred forty-four".