81007881673 has 2 divisors, whose sum is σ = 81007881674. Its totient is φ = 81007881672.

The previous prime is 81007881671. The next prime is 81007881677. The reversal of 81007881673 is 37618870018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 72079899529 + 8927982144 = 268477^2 + 94488^2 .

It is a cyclic number.

It is not a de Polignac number, because 81007881673 - 2¹ = 81007881671 is a prime.

Together with 81007881671, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (81007881671) 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, 40503940836 + 40503940837.

It is an arithmetic number, because the mean of its divisors is an integer number (40503940837).

Almost surely, 2^81007881673 is an apocalyptic number.

It is an amenable number.

81007881673 is a deficient number, since it is larger than the sum of its proper divisors (1).

81007881673 is an equidigital number, since it uses as much as digits as its factorization.

81007881673 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 451584, while the sum is 49.

The spelling of 81007881673 in words is "eighty-one billion, seven million, eight hundred eighty-one thousand, six hundred seventy-three".