81128941491 has 16 divisors (see below), whose sum is σ = 122624042240. Its totient is φ = 47297844000.

The previous prime is 81128941459. The next prime is 81128941573. The reversal of 81128941491 is 19414982118.

It is not a de Polignac number, because 81128941491 - 2⁵ = 81128941459 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 81128941491.

It is not an unprimeable number, because it can be changed into a prime (81128941391) 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, 54742135 + ... + 54743616.

It is an arithmetic number, because the mean of its divisors is an integer number (7664002640).

Almost surely, 2^81128941491 is an apocalyptic number.

81128941491 is a deficient number, since it is larger than the sum of its proper divisors (41495100749).

81128941491 is a wasteful number, since it uses less digits than its factorization.

81128941491 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 109485786.

The product of its digits is 165888, while the sum is 48.

The spelling of 81128941491 in words is "eighty-one billion, one hundred twenty-eight million, nine hundred forty-one thousand, four hundred ninety-one".