81317316672 has 168 divisors, whose sum is σ = 235651020696. Its totient is φ = 26808459264.

The previous prime is 81317316653. The next prime is 81317316679. The reversal of 81317316672 is 27661371318.

It can be written as a sum of positive squares in 4 ways, for example, as 57842174016 + 23475142656 = 240504^2 + 153216^2 .

It is a super-2 number, since 2×81317316672² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81317316679) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 23119458 + ... + 23122974.

It is an arithmetic number, because the mean of its divisors is an integer number (1402684647).

Almost surely, 2^81317316672 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 81317316672, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117825510348).

81317316672 is an abundant number, since it is smaller than the sum of its proper divisors (154333704024).

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

81317316672 is a wasteful number, since it uses less digits than its factorization.

81317316672 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3965 (or 3952 counting only the distinct ones).

The product of its digits is 254016, while the sum is 45.

The spelling of 81317316672 in words is "eighty-one billion, three hundred seventeen million, three hundred sixteen thousand, six hundred seventy-two".