81599349773 has 2 divisors, whose sum is σ = 81599349774. Its totient is φ = 81599349772.

The previous prime is 81599349739. The next prime is 81599349779. The reversal of 81599349773 is 37794399518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 62693649769 + 18905700004 = 250387^2 + 137498^2 .

It is a cyclic number.

It is not a de Polignac number, because 81599349773 - 2¹⁰ = 81599348749 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81599349779) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40799674886 + 40799674887.

It is an arithmetic number, because the mean of its divisors is an integer number (40799674887).

Almost surely, 2^81599349773 is an apocalyptic number.

It is an amenable number.

81599349773 is a deficient number, since it is larger than the sum of its proper divisors (1).

81599349773 is an equidigital number, since it uses as much as digits as its factorization.

81599349773 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51438240, while the sum is 65.

The spelling of 81599349773 in words is "eighty-one billion, five hundred ninety-nine million, three hundred forty-nine thousand, seven hundred seventy-three".