81868188793 has 2 divisors, whose sum is σ = 81868188794. Its totient is φ = 81868188792.

The previous prime is 81868188769. The next prime is 81868188811. The reversal of 81868188793 is 39788186818.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72799054969 + 9069133824 = 269813^2 + 95232^2 .

It is a cyclic number.

It is not a de Polignac number, because 81868188793 - 2¹⁷ = 81868057721 is a prime.

It is not a weakly prime, because it can be changed into another prime (81868188763) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40934094396 + 40934094397.

It is an arithmetic number, because the mean of its divisors is an integer number (40934094397).

Almost surely, 2^81868188793 is an apocalyptic number.

It is an amenable number.

81868188793 is a deficient number, since it is larger than the sum of its proper divisors (1).

81868188793 is an equidigital number, since it uses as much as digits as its factorization.

81868188793 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 37158912, while the sum is 67.

The spelling of 81868188793 in words is "eighty-one billion, eight hundred sixty-eight million, one hundred eighty-eight thousand, seven hundred ninety-three".