81673665782171 has 2 divisors, whose sum is σ = 81673665782172. Its totient is φ = 81673665782170.

The previous prime is 81673665782143. The next prime is 81673665782207. The reversal of 81673665782171 is 17128756637618.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81673665782171 is a prime.

It is not a weakly prime, because it can be changed into another prime (81673665782971) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40836832891085 + 40836832891086.

It is an arithmetic number, because the mean of its divisors is an integer number (40836832891086).

Almost surely, 2^{81673665782171} is an apocalyptic number.

81673665782171 is a deficient number, since it is larger than the sum of its proper divisors (1).

81673665782171 is an equidigital number, since it uses as much as digits as its factorization.

81673665782171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 142248960, while the sum is 68.

The spelling of 81673665782171 in words is "eighty-one trillion, six hundred seventy-three billion, six hundred sixty-five million, seven hundred eighty-two thousand, one hundred seventy-one".