9871991789 has 6 divisors (see below), whose sum is σ = 10851032430. Its totient is φ = 8974537880.

The previous prime is 9871991777. The next prime is 9871991807.

9871991789 is nontrivially palindromic in base 10.

It can be written as a sum of positive squares in only one way, i.e., 8649930025 + 1222061764 = 93005^2 + 34958^2 .

It is not a de Polignac number, because 9871991789 - 2⁸ = 9871991533 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9871991189) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 40793234 + ... + 40793475.

It is an arithmetic number, because the mean of its divisors is an integer number (1808505405).

Almost surely, 2^9871991789 is an apocalyptic number.

It is an amenable number.

9871991789 is a deficient number, since it is larger than the sum of its proper divisors (979040641).

9871991789 is a wasteful number, since it uses less digits than its factorization.

9871991789 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81586731 (or 81586720 counting only the distinct ones).

The product of its digits is 20575296, while the sum is 68.

The square root of 9871991789 is about 99357.8974666835. The cubic root of 9871991789 is about 2145.2023390104.

The spelling of 9871991789 in words is "nine billion, eight hundred seventy-one million, nine hundred ninety-one thousand, seven hundred eighty-nine".