81128171 has 2 divisors, whose sum is σ = 81128172. Its totient is φ = 81128170.

The previous prime is 81128137. The next prime is 81128183. The reversal of 81128171 is 17182118.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 81128171 - 2¹⁰ = 81127147 is a prime.

It is not a weakly prime, because it can be changed into another prime (81121171) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40564085 + 40564086.

It is an arithmetic number, because the mean of its divisors is an integer number (40564086).

Almost surely, 2^81128171 is an apocalyptic number.

81128171 is a deficient number, since it is larger than the sum of its proper divisors (1).

81128171 is an equidigital number, since it uses as much as digits as its factorization.

81128171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 896, while the sum is 29.

The square root of 81128171 is about 9007.1177964985. The cubic root of 81128171 is about 432.9029663432.

It can be divided in two parts, 811 and 28171, that added together give a palindrome (28982).

The spelling of 81128171 in words is "eighty-one million, one hundred twenty-eight thousand, one hundred seventy-one".