18081666 has 12 divisors (see below), whose sum is σ = 39176982. Its totient is φ = 6027216.

The previous prime is 18081653. The next prime is 18081667. The reversal of 18081666 is 66618081.

It can be written as a sum of positive squares in only one way, i.e., 14220441 + 3861225 = 3771^2 + 1965^2 .

It is a super-3 number, since 3×18081666³ (a number of 23 digits) contains 333 as substring.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 18081666.

It is not an unprimeable number, because it can be changed into a prime (18081667) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 502251 + ... + 502286.

Almost surely, 2^18081666 is an apocalyptic number.

18081666 is an abundant number, since it is smaller than the sum of its proper divisors (21095316).

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

18081666 is a wasteful number, since it uses less digits than its factorization.

18081666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1004545 (or 1004542 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 36.

The square root of 18081666 is about 4252.2542257019. The cubic root of 18081666 is about 262.4698849806.

The spelling of 18081666 in words is "eighteen million, eighty-one thousand, six hundred sixty-six".