81549728 has 24 divisors (see below), whose sum is σ = 172901988. Its totient is φ = 37638144.

The previous prime is 81549703. The next prime is 81549733. The reversal of 81549728 is 82794518.

It can be written as a sum of positive squares in 2 ways, for example, as 81504784 + 44944 = 9028^2 + 212^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 97601 + ... + 98432.

Almost surely, 2^81549728 is an apocalyptic number.

It is an amenable number.

81549728 is an abundant number, since it is smaller than the sum of its proper divisors (91352260).

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

81549728 is a wasteful number, since it uses less digits than its factorization.

81549728 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 196056 (or 196048 counting only the distinct ones).

The product of its digits is 161280, while the sum is 44.

The square root of 81549728 is about 9030.4888018313. The cubic root of 81549728 is about 433.6514860137.

The spelling of 81549728 in words is "eighty-one million, five hundred forty-nine thousand, seven hundred twenty-eight".