81047856 has 20 divisors (see below), whose sum is σ = 209373752. Its totient is φ = 27015936.

The previous prime is 81047831. The next prime is 81047861. The reversal of 81047856 is 65874018.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 844201 + ... + 844296.

Almost surely, 2^81047856 is an apocalyptic number.

It is an amenable number.

81047856 is an abundant number, since it is smaller than the sum of its proper divisors (128325896).

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

81047856 is a wasteful number, since it uses less digits than its factorization.

81047856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1688508 (or 1688502 counting only the distinct ones).

The product of its (nonzero) digits is 53760, while the sum is 39.

The square root of 81047856 is about 9002.6582740877. The cubic root of 81047856 is about 432.7600645579.

The spelling of 81047856 in words is "eighty-one million, forty-seven thousand, eight hundred fifty-six".