81444481020 has 480 divisors, whose sum is σ = 303671047680. Its totient is φ = 17878371840.

The previous prime is 81444481009. The next prime is 81444481073. The reversal of 81444481020 is 2018444418.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 159 ways as a sum of consecutive naturals, for example, 74650675 + ... + 74651765.

It is an arithmetic number, because the mean of its divisors is an integer number (632648016).

Almost surely, 2^81444481020 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 81444481020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151835523840).

81444481020 is an abundant number, since it is smaller than the sum of its proper divisors (222226566660).

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

81444481020 is a wasteful number, since it uses less digits than its factorization.

81444481020 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1375 (or 1364 counting only the distinct ones).

The product of its (nonzero) digits is 32768, while the sum is 36.

The spelling of 81444481020 in words is "eighty-one billion, four hundred forty-four million, four hundred eighty-one thousand, twenty".