81220620800 has 270 divisors, whose sum is σ = 222157271259. Its totient is φ = 29405798400.

The previous prime is 81220620799. The next prime is 81220620829. The reversal of 81220620800 is 802602218.

It is a powerful number, because all its prime factors have an exponent greater than 1 and also an Achilles number because it is not a perfect power.

It can be written as a sum of positive squares in 5 ways, for example, as 68493170944 + 12727449856 = 261712^2 + 112816^2 .

It is an ABA number since it can be written as A⋅B^A, here for A=2, B=201520.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 354675086 + ... + 354675314.

Almost surely, 2^81220620800 is an apocalyptic number.

81220620800 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 81220620800

81220620800 is an abundant number, since it is smaller than the sum of its proper divisors (140936650459).

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

81220620800 is an equidigital number, since it uses as much as digits as its factorization.

81220620800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 508 (or 247 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 29.

The spelling of 81220620800 in words is "eighty-one billion, two hundred twenty million, six hundred twenty thousand, eight hundred".