9991171 has 4 divisors (see below), whose sum is σ = 10020312. Its totient is φ = 9962032.

The previous prime is 9991159. The next prime is 9991183. The reversal of 9991171 is 1711999.

9991171 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1711999 = 293 ⋅5843.

It is an interprime number because it is at equal distance from previous prime (9991159) and next prime (9991183).

It is a cyclic number.

It is not a de Polignac number, because 9991171 - 2⁵ = 9991139 is a prime.

It is an Ulam number.

It is a Duffinian number.

9991171 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 9991171.

It is not an unprimeable number, because it can be changed into a prime (9991141) 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, 14050 + ... + 14743.

It is an arithmetic number, because the mean of its divisors is an integer number (2505078).

Almost surely, 2^9991171 is an apocalyptic number.

9991171 is a deficient number, since it is larger than the sum of its proper divisors (29141).

9991171 is a wasteful number, since it uses less digits than its factorization.

9991171 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29140.

The product of its digits is 5103, while the sum is 37.

The square root of 9991171 is about 3160.8813644299. The cubic root of 9991171 is about 215.3800453210.

The spelling of 9991171 in words is "nine million, nine hundred ninety-one thousand, one hundred seventy-one".