19887878640 has 80 divisors (see below), whose sum is σ = 70459918848. Its totient is φ = 4545800448.

The previous prime is 19887878611. The next prime is 19887878641. The reversal of 19887878640 is 4687878891.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19887878641) 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, 5917332 + ... + 5920691.

Almost surely, 2^19887878640 is an apocalyptic number.

19887878640 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

19887878640 is an abundant number, since it is smaller than the sum of its proper divisors (50572040208).

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

19887878640 is a wasteful number, since it uses less digits than its factorization.

19887878640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11838046 (or 11838040 counting only the distinct ones).

The product of its (nonzero) digits is 43352064, while the sum is 66.

The spelling of 19887878640 in words is "nineteen billion, eight hundred eighty-seven million, eight hundred seventy-eight thousand, six hundred forty".