218211985 has 8 divisors (see below), whose sum is σ = 262100520. Its totient is φ = 174405504.

The previous prime is 218211947. The next prime is 218211997. The reversal of 218211985 is 589112812.

It is a Cunningham number, because it is equal to 14772²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 54346384 + 163865601 = 7372^2 + 12801^2 .

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 218211985 - 2⁷ = 218211857 is a prime.

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 in 7 ways as a sum of consecutive naturals, for example, 14500 + ... + 25429.

It is an arithmetic number, because the mean of its divisors is an integer number (32762565).

Almost surely, 2^218211985 is an apocalyptic number.

It is an amenable number.

218211985 is a deficient number, since it is larger than the sum of its proper divisors (43888535).

218211985 is a wasteful number, since it uses less digits than its factorization.

218211985 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41027.

The product of its digits is 11520, while the sum is 37.

The square root of 218211985 is about 14772.0000338478. Note that the first 4 decimals coincide. The cubic root of 218211985 is about 602.0411823425.

The spelling of 218211985 in words is "two hundred eighteen million, two hundred eleven thousand, nine hundred eighty-five".