999999871 has 12 divisors (see below), whose sum is σ = 1105888032. Its totient is φ = 903429696.

The previous prime is 999999797. The next prime is 999999883. The reversal of 999999871 is 178999999.

It is not a de Polignac number, because 999999871 - 2¹⁵ = 999967103 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 999999871.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (999997871) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 55006 + ... + 70891.

It is an arithmetic number, because the mean of its divisors is an integer number (92157336).

Almost surely, 2^999999871 is an apocalyptic number.

999999871 is a deficient number, since it is larger than the sum of its proper divisors (105888161).

999999871 is a wasteful number, since it uses less digits than its factorization.

999999871 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 125970 (or 125957 counting only the distinct ones).

The product of its digits is 29760696, while the sum is 70.

The square root of 999999871 is about 31622.7745620146. The cubic root of 999999871 is about 999.9999570000. Note that the first 4 decimals are identical.

The spelling of 999999871 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, eight hundred seventy-one".