81216550396800 has 1152 divisors, whose sum is σ = 356965957508160. Its totient is φ = 17121871134720.

The previous prime is 81216550396769. The next prime is 81216550396841. The reversal of 81216550396800 is 869305561218.

81216550396800 is a `hidden beast` number, since 8 + 1 + 2 + 1 + 6 + 550 + 3 + 9 + 6 + 80 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (1152).

It is a super-2 number, since 2×81216550396800² (a number of 29 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 3399165654 + ... + 3399189546.

Almost surely, 2^{81216550396800} is an apocalyptic number.

81216550396800 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 81216550396800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (178482978754080).

81216550396800 is an abundant number, since it is smaller than the sum of its proper divisors (275749407111360).

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

81216550396800 is a wasteful number, since it uses less digits than its factorization.

81216550396800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25240 (or 25220 counting only the distinct ones).

The product of its (nonzero) digits is 3110400, while the sum is 54.

The spelling of 81216550396800 in words is "eighty-one trillion, two hundred sixteen billion, five hundred fifty million, three hundred ninety-six thousand, eight hundred".