81447181672 has 32 divisors (see below), whose sum is σ = 156310308000. Its totient is φ = 39764983104.

The previous prime is 81447181603. The next prime is 81447181691. The reversal of 81447181672 is 27618174418.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1218579 + ... + 1283677.

It is an arithmetic number, because the mean of its divisors is an integer number (4884697125).

Almost surely, 2^81447181672 is an apocalyptic number.

It is an amenable number.

81447181672 is a deficient number, since it is larger than the sum of its proper divisors (74863126328).

81447181672 is a wasteful number, since it uses less digits than its factorization.

81447181672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 68785 (or 68781 counting only the distinct ones).

The product of its digits is 602112, while the sum is 49.

The spelling of 81447181672 in words is "eighty-one billion, four hundred forty-seven million, one hundred eighty-one thousand, six hundred seventy-two".