20163778866 has 96 divisors (see below), whose sum is σ = 54661920768. Its totient is φ = 5218737120.

The previous prime is 20163778847. The next prime is 20163778867. The reversal of 20163778866 is 66887736102.

20163778866 is a `hidden beast` number, since 201 + 6 + 377 + 8 + 8 + 66 = 666.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (20163778867) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 366535 + ... + 417941.

It is an arithmetic number, because the mean of its divisors is an integer number (569395008).

Almost surely, 2^20163778866 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20163778866, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27330960384).

20163778866 is an abundant number, since it is smaller than the sum of its proper divisors (34498141902).

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

20163778866 is a wasteful number, since it uses less digits than its factorization.

20163778866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51716 (or 51713 counting only the distinct ones).

The product of its (nonzero) digits is 4064256, while the sum is 54.

The spelling of 20163778866 in words is "twenty billion, one hundred sixty-three million, seven hundred seventy-eight thousand, eight hundred sixty-six".