9878989891 has 2 divisors, whose sum is σ = 9878989892. Its totient is φ = 9878989890.

The previous prime is 9878989873. The next prime is 9878989907. The reversal of 9878989891 is 1989898789.

It is a strong prime.

It is an emirp because it is prime and its reverse (1989898789) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 9878989891 - 2⁵ = 9878989859 is a prime.

It is not a weakly prime, because it can be changed into another prime (9878989801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4939494945 + 4939494946.

It is an arithmetic number, because the mean of its divisors is an integer number (4939494946).

Almost surely, 2^9878989891 is an apocalyptic number.

9878989891 is a deficient number, since it is larger than the sum of its proper divisors (1).

9878989891 is an equidigital number, since it uses as much as digits as its factorization.

9878989891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 188116992, while the sum is 76.

The square root of 9878989891 is about 99393.1078646804. The cubic root of 9878989891 is about 2145.7091195115.

The spelling of 9878989891 in words is "nine billion, eight hundred seventy-eight million, nine hundred eighty-nine thousand, eight hundred ninety-one".