81668768953 has 2 divisors, whose sum is σ = 81668768954. Its totient is φ = 81668768952.

The previous prime is 81668768933. The next prime is 81668769023. The reversal of 81668768953 is 35986786618.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 41391088704 + 40277680249 = 203448^2 + 200693^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81668768953 is a prime.

It is not a weakly prime, because it can be changed into another prime (81668768933) 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, 40834384476 + 40834384477.

It is an arithmetic number, because the mean of its divisors is an integer number (40834384477).

Almost surely, 2^81668768953 is an apocalyptic number.

It is an amenable number.

81668768953 is a deficient number, since it is larger than the sum of its proper divisors (1).

81668768953 is an equidigital number, since it uses as much as digits as its factorization.

81668768953 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 104509440, while the sum is 67.

The spelling of 81668768953 in words is "eighty-one billion, six hundred sixty-eight million, seven hundred sixty-eight thousand, nine hundred fifty-three".