81445440000 has 400 divisors, whose sum is σ = 277578921312. Its totient is φ = 21202944000.

The previous prime is 81445439989. The next prime is 81445440017. The reversal of 81445440000 is 4454418.

It is a tau number, because it is divible by the number of its divisors (400).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a self number, because there is not a number n which added to its sum of digits gives 81445440000.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 41279014 + ... + 41280986.

Almost surely, 2^81445440000 is an apocalyptic number.

81445440000 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 81445440000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138789460656).

81445440000 is an abundant number, since it is smaller than the sum of its proper divisors (196133481312).

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

81445440000 is an equidigital number, since it uses as much as digits as its factorization.

81445440000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2057 (or 2026 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 30.

Adding to 81445440000 its reverse (4454418), we get a palindrome (81449894418).

The spelling of 81445440000 in words is "eighty-one billion, four hundred forty-five million, four hundred forty thousand".