81179327520 has 480 divisors, whose sum is σ = 304862065200. Its totient is φ = 20272840704.

The previous prime is 81179327483. The next prime is 81179327531. The reversal of 81179327520 is 2572397118.

81179327520 is a `hidden beast` number, since 8 + 1 + 17 + 93 + 27 + 520 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 79801730064 + 1377597456 = 282492^2 + 37116^2 .

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 50452476 + ... + 50454084.

Almost surely, 2^81179327520 is an apocalyptic number.

81179327520 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 81179327520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (152431032600).

81179327520 is an abundant number, since it is smaller than the sum of its proper divisors (223682737680).

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

81179327520 is a wasteful number, since it uses less digits than its factorization.

81179327520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1882 (or 1865 counting only the distinct ones).

The product of its (nonzero) digits is 211680, while the sum is 45.

The spelling of 81179327520 in words is "eighty-one billion, one hundred seventy-nine million, three hundred twenty-seven thousand, five hundred twenty".