19887799778891 has 8 divisors (see below), whose sum is σ = 21707528097024. Its totient is φ = 18070029214120.

The previous prime is 19887799778807. The next prime is 19887799778969.

19887799778891 is nontrivially palindromic in base 10.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-19887799778891 is a prime.

It is not an unprimeable number, because it can be changed into a prime (19887799478891) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 489417095 + ... + 489457728.

It is an arithmetic number, because the mean of its divisors is an integer number (2713441012128).

Almost surely, 2^{19887799778891} is an apocalyptic number.

19887799778891 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

19887799778891 is a deficient number, since it is larger than the sum of its proper divisors (1819728318133).

19887799778891 is a wasteful number, since it uses less digits than its factorization.

19887799778891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 978876681.

The product of its digits is 64524128256, while the sum is 98.

The spelling of 19887799778891 in words is "nineteen trillion, eight hundred eighty-seven billion, seven hundred ninety-nine million, seven hundred seventy-eight thousand, eight hundred ninety-one".