2180978666 has 16 divisors (see below), whose sum is σ = 3299200800. Its totient is φ = 1081265328.

The previous prime is 2180978663. The next prime is 2180978677. The reversal of 2180978666 is 6668790812.

It is a Smith number, since the sum of its digits (53) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (2180978663) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 234236 + ... + 243368.

It is an arithmetic number, because the mean of its divisors is an integer number (206200050).

Almost surely, 2^2180978666 is an apocalyptic number.

2180978666 is a deficient number, since it is larger than the sum of its proper divisors (1118222134).

2180978666 is a wasteful number, since it uses less digits than its factorization.

2180978666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10133.

The product of its (nonzero) digits is 1741824, while the sum is 53.

The square root of 2180978666 is about 46700.9493051266. The cubic root of 2180978666 is about 1296.8322609390.

The spelling of 2180978666 in words is "two billion, one hundred eighty million, nine hundred seventy-eight thousand, six hundred sixty-six".