81186481584 has 240 divisors, whose sum is σ = 251973615712. Its totient is φ = 24240218112.

The previous prime is 81186481561. The next prime is 81186481609. The reversal of 81186481584 is 48518468118.

81186481584 is a `hidden beast` number, since 8 + 1 + 1 + 86 + 481 + 5 + 84 = 666.

It is a super-2 number, since 2×81186481584² (a number of 23 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 81186481584.

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 47 ways as a sum of consecutive naturals, for example, 29989959 + ... + 29992665.

Almost surely, 2^81186481584 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 81186481584, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (125986807856).

81186481584 is an abundant number, since it is smaller than the sum of its proper divisors (170787134128).

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

81186481584 is a wasteful number, since it uses less digits than its factorization.

81186481584 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3204 (or 3195 counting only the distinct ones).

The product of its digits is 1966080, while the sum is 54.

The spelling of 81186481584 in words is "eighty-one billion, one hundred eighty-six million, four hundred eighty-one thousand, five hundred eighty-four".