81533426688 has 704 divisors, whose sum is σ = 290837760000. Its totient is φ = 22072393728.

The previous prime is 81533426671. The next prime is 81533426693. The reversal of 81533426688 is 88662433518.

81533426688 is a `hidden beast` number, since 8 + 1 + 533 + 4 + 26 + 6 + 88 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

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 63 ways as a sum of consecutive naturals, for example, 409715613 + ... + 409715811.

Almost surely, 2^81533426688 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 81533426688, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (145418880000).

81533426688 is an abundant number, since it is smaller than the sum of its proper divisors (209304333312).

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

81533426688 is a wasteful number, since it uses less digits than its factorization.

81533426688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 337 (or 313 counting only the distinct ones).

The product of its digits is 6635520, while the sum is 54.

The spelling of 81533426688 in words is "eighty-one billion, five hundred thirty-three million, four hundred twenty-six thousand, six hundred eighty-eight".