216668778 has 16 divisors (see below), whose sum is σ = 442558080. Its totient is φ = 70686176.

The previous prime is 216668603. The next prime is 216668839. The reversal of 216668778 is 877866612.

216668778 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Smith number, since the sum of its digits (51) 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 a self number, because there is not a number n which added to its sum of digits gives 216668778.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 383883 + ... + 384446.

It is an arithmetic number, because the mean of its divisors is an integer number (27659880).

Almost surely, 2^216668778 is an apocalyptic number.

216668778 is an abundant number, since it is smaller than the sum of its proper divisors (225889302).

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

216668778 is a wasteful number, since it uses less digits than its factorization.

216668778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768381.

The product of its digits is 1354752, while the sum is 51.

The square root of 216668778 is about 14719.6731621324. The cubic root of 216668778 is about 600.6186008913.

The spelling of 216668778 in words is "two hundred sixteen million, six hundred sixty-eight thousand, seven hundred seventy-eight".