991171 has 2 divisors, whose sum is σ = 991172. Its totient is φ = 991170.

The previous prime is 991147. The next prime is 991181. The reversal of 991171 is 171199.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 991171 - 2⁷ = 991043 is a prime.

It is a zygodrome in base 2.

It is not a weakly prime, because it can be changed into another prime (991181) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495585 + 495586.

It is an arithmetic number, because the mean of its divisors is an integer number (495586).

2⁹⁹¹¹⁷¹ is an apocalyptic number.

991171 is a deficient number, since it is larger than the sum of its proper divisors (1).

991171 is an equidigital number, since it uses as much as digits as its factorization.

991171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 567, while the sum is 28.

The square root of 991171 is about 995.5757128416. The cubic root of 991171 is about 99.7048296016.

Adding to 991171 its sum of digits (28), we get a palindrome (991199).

The spelling of 991171 in words is "nine hundred ninety-one thousand, one hundred seventy-one".