81329768660 has 96 divisors (see below), whose sum is σ = 208279760640. Its totient is φ = 26054949888.

The previous prime is 81329768647. The next prime is 81329768671. The reversal of 81329768660 is 6686792318.

It is a super-2 number, since 2×81329768660² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81329768596 and 81329768605.

It is a congruent 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 31 ways as a sum of consecutive naturals, for example, 15239 + ... + 403598.

It is an arithmetic number, because the mean of its divisors is an integer number (2169580840).

Almost surely, 2^81329768660 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 81329768660, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (104139880320).

81329768660 is an abundant number, since it is smaller than the sum of its proper divisors (126949991980).

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

81329768660 is a wasteful number, since it uses less digits than its factorization.

81329768660 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 418945 (or 418943 counting only the distinct ones).

The product of its (nonzero) digits is 5225472, while the sum is 56.

The spelling of 81329768660 in words is "eighty-one billion, three hundred twenty-nine million, seven hundred sixty-eight thousand, six hundred sixty".