999999971 has 4 divisors (see below), whose sum is σ = 1005181512. Its totient is φ = 994818432.

The previous prime is 999999937. The next prime is 1000000007. The reversal of 999999971 is 179999999.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 179999999 = 79 ⋅2278481.

It is a cyclic number.

It is not a de Polignac number, because 999999971 - 2²² = 995805667 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 = 999999895 and 999999904.

It is not an unprimeable number, because it can be changed into a prime (999993971) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2590481 + ... + 2590866.

It is an arithmetic number, because the mean of its divisors is an integer number (251295378).

Almost surely, 2^999999971 is an apocalyptic number.

999999971 is a deficient number, since it is larger than the sum of its proper divisors (5181541).

999999971 is a wasteful number, since it uses less digits than its factorization.

999999971 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5181540.

The product of its digits is 33480783, while the sum is 71.

The square root of 999999971 is about 31622.7761431535. The cubic root of 999999971 is about 999.9999903333. Note that the first 5 decimals are identical.

The spelling of 999999971 in words is "nine hundred ninety-nine million, nine hundred ninety-nine thousand, nine hundred seventy-one".