81115109680 has 120 divisors (see below), whose sum is σ = 218552194800. Its totient is φ = 27761233920.

The previous prime is 81115109633. The next prime is 81115109683. The reversal of 81115109680 is 8690151118.

It is a super-2 number, since 2×81115109680² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is not an unprimeable number, because it can be changed into a prime (81115109683) 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, 94846 + ... + 413794.

It is an arithmetic number, because the mean of its divisors is an integer number (1821268290).

Almost surely, 2^81115109680 is an apocalyptic number.

81115109680 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81115109680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (109276097400).

81115109680 is an abundant number, since it is smaller than the sum of its proper divisors (137437085120).

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

81115109680 is a wasteful number, since it uses less digits than its factorization.

81115109680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 319007 (or 318984 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 40.

The spelling of 81115109680 in words is "eighty-one billion, one hundred fifteen million, one hundred nine thousand, six hundred eighty".