81571317672 has 32 divisors (see below), whose sum is σ = 219615086880. Its totient is φ = 25098866880.

The previous prime is 81571317661. The next prime is 81571317689. The reversal of 81571317672 is 27671317518.

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, 130722954 + ... + 130723577.

It is an arithmetic number, because the mean of its divisors is an integer number (6862971465).

Almost surely, 2^81571317672 is an apocalyptic number.

It is an amenable number.

81571317672 is an abundant number, since it is smaller than the sum of its proper divisors (138043769208).

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

81571317672 is a wasteful number, since it uses less digits than its factorization.

81571317672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 261446553 (or 261446549 counting only the distinct ones).

The product of its digits is 493920, while the sum is 48.

The spelling of 81571317672 in words is "eighty-one billion, five hundred seventy-one million, three hundred seventeen thousand, six hundred seventy-two".