9999999871 has 4 divisors (see below), whose sum is σ = 10322580544. Its totient is φ = 9677419200.

The previous prime is 9999999851. The next prime is 9999999881. The reversal of 9999999871 is 1789999999.

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 9999999871 - 2¹¹ = 9999997823 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a junction number, because it is equal to n+sod(n) for n = 9999999791 and 9999999800.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9999999851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 161290290 + ... + 161290351.

It is an arithmetic number, because the mean of its divisors is an integer number (2580645136).

Almost surely, 2^9999999871 is an apocalyptic number.

9999999871 is a deficient number, since it is larger than the sum of its proper divisors (322580673).

9999999871 is a wasteful number, since it uses less digits than its factorization.

9999999871 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 322580672.

The product of its digits is 267846264, while the sum is 79.

The square root of 9999999871 is about 99999.9993550000. Note that the first 3 decimals coincide. The cubic root of 9999999871 is about 2154.4346807678.

The spelling of 9999999871 in words is "nine billion, nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred seventy-one".