81084840 has 128 divisors (see below), whose sum is σ = 255467520. Its totient is φ = 20563200.

The previous prime is 81084827. The next prime is 81084847. The reversal of 81084840 is 4848018.

It is not an unprimeable number, because it can be changed into a prime (81084847) 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 31 ways as a sum of consecutive naturals, for example, 263967 + ... + 264273.

It is an arithmetic number, because the mean of its divisors is an integer number (1995840).

Almost surely, 2^81084840 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81084840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (127733760).

81084840 is an abundant number, since it is smaller than the sum of its proper divisors (174382680).

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

81084840 is a wasteful number, since it uses less digits than its factorization.

81084840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 423 (or 419 counting only the distinct ones).

The product of its (nonzero) digits is 8192, while the sum is 33.

The square root of 81084840 is about 9004.7120997842. The cubic root of 81084840 is about 432.8258806700.

The spelling of 81084840 in words is "eighty-one million, eighty-four thousand, eight hundred forty".