81197212800 has 768 divisors, whose sum is σ = 308384547840. Its totient is φ = 18585600000.

The previous prime is 81197212787. The next prime is 81197212819. The reversal of 81197212800 is 821279118.

It is a super-3 number, since 3×81197212800³ (a number of 34 digits) contains 333 as substring.

It is an unprimeable number.

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 95 ways as a sum of consecutive naturals, for example, 245308635 + ... + 245308965.

It is an arithmetic number, because the mean of its divisors is an integer number (401542380).

Almost surely, 2^81197212800 is an apocalyptic number.

81197212800 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 81197212800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (154192273920).

81197212800 is an abundant number, since it is smaller than the sum of its proper divisors (227187335040).

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

81197212800 is a wasteful number, since it uses less digits than its factorization.

81197212800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 493 (or 476 counting only the distinct ones).

The product of its (nonzero) digits is 16128, while the sum is 39.

The spelling of 81197212800 in words is "eighty-one billion, one hundred ninety-seven million, two hundred twelve thousand, eight hundred".