81128541517 has 2 divisors, whose sum is σ = 81128541518. Its totient is φ = 81128541516.

The previous prime is 81128541497. The next prime is 81128541553. The reversal of 81128541517 is 71514582118.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 79896110281 + 1232431236 = 282659^2 + 35106^2 .

It is a cyclic number.

It is not a de Polignac number, because 81128541517 - 2²³ = 81120152909 is a prime.

It is a super-2 number, since 2×81128541517² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81128541817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40564270758 + 40564270759.

It is an arithmetic number, because the mean of its divisors is an integer number (40564270759).

Almost surely, 2^81128541517 is an apocalyptic number.

It is an amenable number.

81128541517 is a deficient number, since it is larger than the sum of its proper divisors (1).

81128541517 is an equidigital number, since it uses as much as digits as its factorization.

81128541517 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 89600, while the sum is 43.

The spelling of 81128541517 in words is "eighty-one billion, one hundred twenty-eight million, five hundred forty-one thousand, five hundred seventeen".