218484612721 has 8 divisors (see below), whose sum is σ = 226910837160. Its totient is φ = 210191084928.

The previous prime is 218484612719. The next prime is 218484612733. The reversal of 218484612721 is 127216484812.

It can be written as a sum of positive squares in 4 ways, for example, as 17098177600 + 201386435121 = 130760^2 + 448761^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 218484612721 - 2¹ = 218484612719 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218484612751) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33170806 + ... + 33177391.

It is an arithmetic number, because the mean of its divisors is an integer number (28363854645).

Almost surely, 2^218484612721 is an apocalyptic number.

It is an amenable number.

218484612721 is a deficient number, since it is larger than the sum of its proper divisors (8426224439).

218484612721 is an equidigital number, since it uses as much as digits as its factorization.

218484612721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66348323.

The product of its digits is 344064, while the sum is 46.

The spelling of 218484612721 in words is "two hundred eighteen billion, four hundred eighty-four million, six hundred twelve thousand, seven hundred twenty-one".