81489736512 has 84 divisors (see below), whose sum is σ = 233880626980. Its totient is φ = 27127775232.

The previous prime is 81489736511. The next prime is 81489736571. The reversal of 81489736512 is 21563798418.

81489736512 is a `hidden beast` number, since 8 + 1 + 4 + 8 + 97 + 36 + 512 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 24418437696 + 57071298816 = 156264^2 + 238896^2 .

It is a super-2 number, since 2×81489736512² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81489736511) 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 11 ways as a sum of consecutive naturals, for example, 350958 + ... + 534930.

Almost surely, 2^81489736512 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 81489736512, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116940313490).

81489736512 is an abundant number, since it is smaller than the sum of its proper divisors (152390890468).

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

81489736512 is a wasteful number, since it uses less digits than its factorization.

81489736512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 184760 (or 184747 counting only the distinct ones).

The product of its digits is 2903040, while the sum is 54.

The spelling of 81489736512 in words is "eighty-one billion, four hundred eighty-nine million, seven hundred thirty-six thousand, five hundred twelve".