81168441857 has 2 divisors, whose sum is σ = 81168441858. Its totient is φ = 81168441856.

The previous prime is 81168441829. The next prime is 81168441889. The reversal of 81168441857 is 75814486118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 63234143296 + 17934298561 = 251464^2 + 133919^2 .

It is a cyclic number.

It is not a de Polignac number, because 81168441857 - 2¹⁸ = 81168179713 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81168441799 and 81168441808.

It is not a weakly prime, because it can be changed into another prime (81168441817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40584220928 + 40584220929.

It is an arithmetic number, because the mean of its divisors is an integer number (40584220929).

Almost surely, 2^81168441857 is an apocalyptic number.

It is an amenable number.

81168441857 is a deficient number, since it is larger than the sum of its proper divisors (1).

81168441857 is an equidigital number, since it uses as much as digits as its factorization.

81168441857 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1720320, while the sum is 53.

The spelling of 81168441857 in words is "eighty-one billion, one hundred sixty-eight million, four hundred forty-one thousand, eight hundred fifty-seven".