81549388800 has 792 divisors, whose sum is σ = 332616211200. Its totient is φ = 18896486400.

The previous prime is 81549388793. The next prime is 81549388801. The reversal of 81549388800 is 888394518.

It is a tau number, because it is divible by the number of its divisors (792).

It is not an unprimeable number, because it can be changed into a prime (81549388801) by changing a digit.

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 71 ways as a sum of consecutive naturals, for example, 58290501 + ... + 58291899.

Almost surely, 2^81549388800 is an apocalyptic number.

81549388800 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 81549388800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (166308105600).

81549388800 is an abundant number, since it is smaller than the sum of its proper divisors (251066822400).

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

81549388800 is a wasteful number, since it uses less digits than its factorization.

81549388800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1469 (or 1443 counting only the distinct ones).

The product of its (nonzero) digits is 2211840, while the sum is 54.

The spelling of 81549388800 in words is "eighty-one billion, five hundred forty-nine million, three hundred eighty-eight thousand, eight hundred".