19891129728 has 128 divisors (see below), whose sum is σ = 53969097600. Its totient is φ = 6489169920.

The previous prime is 19891129723. The next prime is 19891129729. The reversal of 19891129728 is 82792119891.

It is a tau number, because it is divible by the number of its divisors (128).

It is a super-2 number, since 2×19891129728² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19891129723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5458275 + ... + 5461917.

It is an arithmetic number, because the mean of its divisors is an integer number (421633575).

Almost surely, 2^19891129728 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19891129728, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26984548800).

19891129728 is an abundant number, since it is smaller than the sum of its proper divisors (34077967872).

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

19891129728 is a wasteful number, since it uses less digits than its factorization.

19891129728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3960 (or 3948 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 57.

The spelling of 19891129728 in words is "nineteen billion, eight hundred ninety-one million, one hundred twenty-nine thousand, seven hundred twenty-eight".