81118728 has 24 divisors (see below), whose sum is σ = 219696750. Its totient is φ = 27039552.

The previous prime is 81118727. The next prime is 81118753. The reversal of 81118728 is 82781118.

It can be written as a sum of positive squares in only one way, i.e., 73925604 + 7193124 = 8598^2 + 2682^2 .

It is a tau number, because it is divible by the number of its divisors (24).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81118692 and 81118701.

It is not an unprimeable number, because it can be changed into a prime (81118721) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 563253 + ... + 563396.

Almost surely, 2^81118728 is an apocalyptic number.

It is an amenable number.

81118728 is an abundant number, since it is smaller than the sum of its proper divisors (138578022).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81118728 is a wasteful number, since it uses less digits than its factorization.

81118728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1126661 (or 1126654 counting only the distinct ones).

The product of its digits is 7168, while the sum is 36.

The square root of 81118728 is about 9006.5935847023. The cubic root of 81118728 is about 432.8861696239.

The spelling of 81118728 in words is "eighty-one million, one hundred eighteen thousand, seven hundred twenty-eight".