81548328989 has 2 divisors, whose sum is σ = 81548328990. Its totient is φ = 81548328988.

The previous prime is 81548328907. The next prime is 81548328997. The reversal of 81548328989 is 98982384518.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 72177120964 + 9371208025 = 268658^2 + 96805^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81548328989 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81548328289) 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, 40774164494 + 40774164495.

It is an arithmetic number, because the mean of its divisors is an integer number (40774164495).

Almost surely, 2^81548328989 is an apocalyptic number.

It is an amenable number.

81548328989 is a deficient number, since it is larger than the sum of its proper divisors (1).

81548328989 is an equidigital number, since it uses as much as digits as its factorization.

81548328989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 39813120, while the sum is 65.

The spelling of 81548328989 in words is "eighty-one billion, five hundred forty-eight million, three hundred twenty-eight thousand, nine hundred eighty-nine".