81544025808 has 450 divisors, whose sum is σ = 289836341586. Its totient is φ = 22065861888.

The previous prime is 81544025803. The next prime is 81544025873. The reversal of 81544025808 is 80852044518.

81544025808 is a `hidden beast` number, since 8 + 1 + 544 + 0 + 25 + 80 + 8 = 666.

It can be written as a sum of positive squares in only one way, i.e., 55042790544 + 26501235264 = 234612^2 + 162792^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81544025803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 89 ways as a sum of consecutive naturals, for example, 22923166 + ... + 22926722.

Almost surely, 2^81544025808 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 81544025808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144918170793).

81544025808 is an abundant number, since it is smaller than the sum of its proper divisors (208292315778).

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

81544025808 is a wasteful number, since it uses less digits than its factorization.

81544025808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3629 (or 3588 counting only the distinct ones).

The product of its (nonzero) digits is 409600, while the sum is 45.

The spelling of 81544025808 in words is "eighty-one billion, five hundred forty-four million, twenty-five thousand, eight hundred eight".