81349687817 has 2 divisors, whose sum is σ = 81349687818. Its totient is φ = 81349687816.

The previous prime is 81349687813. The next prime is 81349687819. The reversal of 81349687817 is 71878694318.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 50030952976 + 31318734841 = 223676^2 + 176971^2 .

It is a cyclic number.

It is not a de Polignac number, because 81349687817 - 2² = 81349687813 is a prime.

Together with 81349687819, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81349687817.

It is not a weakly prime, because it can be changed into another prime (81349687813) 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, 40674843908 + 40674843909.

It is an arithmetic number, because the mean of its divisors is an integer number (40674843909).

Almost surely, 2^81349687817 is an apocalyptic number.

It is an amenable number.

81349687817 is a deficient number, since it is larger than the sum of its proper divisors (1).

81349687817 is an equidigital number, since it uses as much as digits as its factorization.

81349687817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16257024, while the sum is 62.

The spelling of 81349687817 in words is "eighty-one billion, three hundred forty-nine million, six hundred eighty-seven thousand, eight hundred seventeen".