81128743 has 16 divisors (see below), whose sum is σ = 88335360. Its totient is φ = 74221056.

The previous prime is 81128699. The next prime is 81128779. The reversal of 81128743 is 34782118.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 81128743 - 2¹³ = 81120551 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81128699 and 81128708.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81108743) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 114073 + ... + 114781.

It is an arithmetic number, because the mean of its divisors is an integer number (5520960).

Almost surely, 2^81128743 is an apocalyptic number.

81128743 is a deficient number, since it is larger than the sum of its proper divisors (7206617).

81128743 is a wasteful number, since it uses less digits than its factorization.

81128743 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 906.

The product of its digits is 10752, while the sum is 34.

The square root of 81128743 is about 9007.1495491082. The cubic root of 81128743 is about 432.9039837453.

The spelling of 81128743 in words is "eighty-one million, one hundred twenty-eight thousand, seven hundred forty-three".