666181818 has 24 divisors (see below), whose sum is σ = 1482406068. Its totient is φ = 216058752.

The previous prime is 666181801. The next prime is 666181829. The reversal of 666181818 is 818181666.

666181818 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 658076409 + 8105409 = 25653^2 + 2847^2 .

666181818 is a modest number, since divided by 181818 gives 666 as remainder.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 499471 + ... + 500802.

Almost surely, 2^666181818 is an apocalyptic number.

666181818 is an abundant number, since it is smaller than the sum of its proper divisors (816224250).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

666181818 is a wasteful number, since it uses less digits than its factorization.

666181818 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1000318 (or 1000315 counting only the distinct ones).

The product of its digits is 110592, while the sum is 45.

The square root of 666181818 is about 25810.4982129365. The cubic root of 666181818 is about 873.3686362138.

The spelling of 666181818 in words is "six hundred sixty-six million, one hundred eighty-one thousand, eight hundred eighteen".