81266716800 has 480 divisors, whose sum is σ = 301953324420. Its totient is φ = 21522309120.

The previous prime is 81266716789. The next prime is 81266716801. The reversal of 81266716800 is 861766218.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 3987164736 + 77279552064 = 63144^2 + 277992^2 .

It is a tau number, because it is divible by the number of its divisors (480).

It is a Harshad number since it is a multiple of its sum of digits (45).

It is not an unprimeable number, because it can be changed into a prime (81266716801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 40693402 + ... + 40695398.

Almost surely, 2^81266716800 is an apocalyptic number.

81266716800 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 81266716800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (150976662210).

81266716800 is an abundant number, since it is smaller than the sum of its proper divisors (220686607620).

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

81266716800 is a wasteful number, since it uses less digits than its factorization.

81266716800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2190 (or 2164 counting only the distinct ones).

The product of its (nonzero) digits is 193536, while the sum is 45.

The spelling of 81266716800 in words is "eighty-one billion, two hundred sixty-six million, seven hundred sixteen thousand, eight hundred".