81135532800 has 1944 divisors, whose sum is σ = 380317064400. Its totient is φ = 16349921280.

The previous prime is 81135532771. The next prime is 81135532837. The reversal of 81135532800 is 823553118.

81135532800 is a `hidden beast` number, since 8 + 11 + 35 + 532 + 80 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a polite number, since it can be written in 215 ways as a sum of consecutive naturals, for example, 911635156 + ... + 911635244.

It is an arithmetic number, because the mean of its divisors is an integer number (195636350).

Almost surely, 2^81135532800 is an apocalyptic number.

81135532800 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 81135532800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (190158532200).

81135532800 is an abundant number, since it is smaller than the sum of its proper divisors (299181531600).

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

81135532800 is a wasteful number, since it uses less digits than its factorization.

81135532800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 171 (or 142 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The spelling of 81135532800 in words is "eighty-one billion, one hundred thirty-five million, five hundred thirty-two thousand, eight hundred".