218511646081 has 4 divisors (see below), whose sum is σ = 219620842452. Its totient is φ = 217402449712.

The previous prime is 218511646079. The next prime is 218511646159. The reversal of 218511646081 is 180646115812.

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 188264871025 + 30246775056 = 433895^2 + 173916^2 .

It is a cyclic number.

It is not a de Polignac number, because 218511646081 - 2¹ = 218511646079 is a prime.

It is a super-2 number, since 2×218511646081² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (218511646021) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 554597890 + ... + 554598283.

It is an arithmetic number, because the mean of its divisors is an integer number (54905210613).

Almost surely, 2^218511646081 is an apocalyptic number.

It is an amenable number.

218511646081 is a deficient number, since it is larger than the sum of its proper divisors (1109196371).

218511646081 is a wasteful number, since it uses less digits than its factorization.

218511646081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1109196370.

The product of its (nonzero) digits is 92160, while the sum is 43.

The spelling of 218511646081 in words is "two hundred eighteen billion, five hundred eleven million, six hundred forty-six thousand, eighty-one".