218528081 has 4 divisors (see below), whose sum is σ = 231382692. Its totient is φ = 205673472.

The previous prime is 218528039. The next prime is 218528087. The reversal of 218528081 is 180825812.

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

It can be written as a sum of positive squares in 2 ways, for example, as 126675025 + 91853056 = 11255^2 + 9584^2 .

It is a cyclic number.

It is not a de Polignac number, because 218528081 - 2¹⁴ = 218511697 is a prime.

It is a super-2 number, since 2×218528081² = 95509044371085122, which contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (218528087) 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 3 ways as a sum of consecutive naturals, for example, 6427280 + ... + 6427313.

It is an arithmetic number, because the mean of its divisors is an integer number (57845673).

Almost surely, 2^218528081 is an apocalyptic number.

It is an amenable number.

218528081 is a deficient number, since it is larger than the sum of its proper divisors (12854611).

218528081 is a wasteful number, since it uses less digits than its factorization.

218528081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12854610.

The product of its (nonzero) digits is 10240, while the sum is 35.

The square root of 218528081 is about 14782.6953225723. The cubic root of 218528081 is about 602.3317422985.

The spelling of 218528081 in words is "two hundred eighteen million, five hundred twenty-eight thousand, eighty-one".