19661728780 has 12 divisors (see below), whose sum is σ = 41289630480. Its totient is φ = 7864691504.

The previous prime is 19661728769. The next prime is 19661728781. The reversal of 19661728780 is 8782716691.

It is not an unprimeable number, because it can be changed into a prime (19661728781) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 491543200 + ... + 491543239.

It is an arithmetic number, because the mean of its divisors is an integer number (3440802540).

Almost surely, 2^19661728780 is an apocalyptic number.

19661728780 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19661728780 is an abundant number, since it is smaller than the sum of its proper divisors (21627901700).

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

19661728780 is a wasteful number, since it uses less digits than its factorization.

19661728780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 983086448 (or 983086446 counting only the distinct ones).

The product of its (nonzero) digits is 2032128, while the sum is 55.

The spelling of 19661728780 in words is "nineteen billion, six hundred sixty-one million, seven hundred twenty-eight thousand, seven hundred eighty".