81558816 has 24 divisors (see below), whose sum is σ = 214092144. Its totient is φ = 27186240.

The previous prime is 81558797. The next prime is 81558823. The reversal of 81558816 is 61885518.

It is a happy number.

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

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 424690 + ... + 424881.

It is an arithmetic number, because the mean of its divisors is an integer number (8920506).

Almost surely, 2^81558816 is an apocalyptic number.

It is an amenable number.

81558816 is an abundant number, since it is smaller than the sum of its proper divisors (132533328).

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

81558816 is a wasteful number, since it uses less digits than its factorization.

81558816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849584 (or 849576 counting only the distinct ones).

The product of its digits is 76800, while the sum is 42.

The square root of 81558816 is about 9030.9919720925. The cubic root of 81558816 is about 433.6675942968.

The spelling of 81558816 in words is "eighty-one million, five hundred fifty-eight thousand, eight hundred sixteen".