81091465806400 has 567 divisors, whose sum is σ = 240609795066849. Its totient is φ = 26819865784320.

The previous prime is 81091465806367. The next prime is 81091465806413. The reversal of 81091465806400 is 460856419018.

The square root of 81091465806400 is 9005080.

It is a perfect power (a square), and thus also a powerful number.

81091465806400 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 13 ways, for example, as 81083397455424 + 8068350976 = 9004632^2 + 89824^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 73121249046 + ... + 73121250154.

Almost surely, 2^{81091465806400} is an apocalyptic number.

81091465806400 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

81091465806400 is the 9005080-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81091465806400

81091465806400 is an abundant number, since it is smaller than the sum of its proper divisors (159518329260449).

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

81091465806400 is an equidigital number, since it uses as much as digits as its factorization.

81091465806400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2312 (or 1152 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 52.

The spelling of 81091465806400 in words is "eighty-one trillion, ninety-one billion, four hundred sixty-five million, eight hundred six thousand, four hundred".