19897861984 has 144 divisors (see below), whose sum is σ = 53536983696. Its totient is φ = 7155993600.

The previous prime is 19897861957. The next prime is 19897862003. The reversal of 19897861984 is 48916879891.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 179854 + ... + 268594.

It is an arithmetic number, because the mean of its divisors is an integer number (371784609).

Almost surely, 2^19897861984 is an apocalyptic number.

19897861984 is a gapful number since it is divisible by the number (14) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19897861984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26768491848).

19897861984 is an abundant number, since it is smaller than the sum of its proper divisors (33639121712).

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

19897861984 is a wasteful number, since it uses less digits than its factorization.

19897861984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88789 (or 88774 counting only the distinct ones).

The product of its digits is 62705664, while the sum is 70.

The spelling of 19897861984 in words is "nineteen billion, eight hundred ninety-seven million, eight hundred sixty-one thousand, nine hundred eighty-four".