19981730728 has 32 divisors (see below), whose sum is σ = 37909224360. Its totient is φ = 9872916480.

The previous prime is 19981730719. The next prime is 19981730753. The reversal of 19981730728 is 82703718991.

It can be written as a sum of positive squares in 4 ways, for example, as 18835366564 + 1146364164 = 137242^2 + 33858^2 .

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, 503118 + ... + 541378.

Almost surely, 2^19981730728 is an apocalyptic number.

It is an amenable number.

19981730728 is a deficient number, since it is larger than the sum of its proper divisors (17927493632).

19981730728 is a wasteful number, since it uses less digits than its factorization.

19981730728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39037 (or 39033 counting only the distinct ones).

The product of its (nonzero) digits is 1524096, while the sum is 55.

The spelling of 19981730728 in words is "nineteen billion, nine hundred eighty-one million, seven hundred thirty thousand, seven hundred twenty-eight".