218330821 has 16 divisors (see below), whose sum is σ = 233107200. Its totient is φ = 204095808.

The previous prime is 218330807. The next prime is 218330831. The reversal of 218330821 is 128033812.

218330821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 218330821 - 2⁹ = 218330309 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 218330821.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (218330831) 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, 303300 + ... + 304018.

It is an arithmetic number, because the mean of its divisors is an integer number (14569200).

Almost surely, 2^218330821 is an apocalyptic number.

It is an amenable number.

218330821 is a deficient number, since it is larger than the sum of its proper divisors (14776379).

218330821 is a wasteful number, since it uses less digits than its factorization.

218330821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1068.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 218330821 is about 14776.0218259178. The cubic root of 218330821 is about 602.1504509855.

The spelling of 218330821 in words is "two hundred eighteen million, three hundred thirty thousand, eight hundred twenty-one".