19897806887 has 4 divisors (see below), whose sum is σ = 22740350736. Its totient is φ = 17055263040.

The previous prime is 19897806853. The next prime is 19897806923. The reversal of 19897806887 is 78860879891.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 19897806887 - 2⁸ = 19897806631 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 19897806887.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19897806827) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 1421271914 + ... + 1421271927.

It is an arithmetic number, because the mean of its divisors is an integer number (5685087684).

Almost surely, 2^19897806887 is an apocalyptic number.

19897806887 is a deficient number, since it is larger than the sum of its proper divisors (2842543849).

19897806887 is an equidigital number, since it uses as much as digits as its factorization.

19897806887 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2842543848.

The product of its (nonzero) digits is 97542144, while the sum is 71.

The spelling of 19897806887 in words is "nineteen billion, eight hundred ninety-seven million, eight hundred six thousand, eight hundred eighty-seven".