19801717866 has 32 divisors (see below), whose sum is σ = 50290078080. Its totient is φ = 5657633568.

The previous prime is 19801717849. The next prime is 19801717867. The reversal of 19801717866 is 66871710891.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (19801717867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 26192371 + ... + 26193126.

It is an arithmetic number, because the mean of its divisors is an integer number (1571564940).

Almost surely, 2^19801717866 is an apocalyptic number.

19801717866 is an abundant number, since it is smaller than the sum of its proper divisors (30488360214).

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

19801717866 is a wasteful number, since it uses less digits than its factorization.

19801717866 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52385515 (or 52385509 counting only the distinct ones).

The product of its (nonzero) digits is 1016064, while the sum is 54.

The spelling of 19801717866 in words is "nineteen billion, eight hundred one million, seven hundred seventeen thousand, eight hundred sixty-six".