81325531872 has 240 divisors, whose sum is σ = 272727644112. Its totient is φ = 23551119360.

The previous prime is 81325531829. The next prime is 81325531933. The reversal of 81325531872 is 27813552318.

81325531872 is a `hidden beast` number, since 8 + 1 + 32 + 5 + 531 + 87 + 2 = 666.

It is a super-2 number, since 2×81325531872² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 39 ways as a sum of consecutive naturals, for example, 501847 + ... + 643817.

Almost surely, 2^81325531872 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 81325531872, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (136363822056).

81325531872 is an abundant number, since it is smaller than the sum of its proper divisors (191402112240).

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

81325531872 is a wasteful number, since it uses less digits than its factorization.

81325531872 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 142023 (or 142006 counting only the distinct ones).

The product of its digits is 403200, while the sum is 45.

The spelling of 81325531872 in words is "eighty-one billion, three hundred twenty-five million, five hundred thirty-one thousand, eight hundred seventy-two".