81173681971200 has 2016 divisors, whose sum is σ = 369086342140800. Its totient is φ = 17125374689280.

The previous prime is 81173681971183. The next prime is 81173681971241. The reversal of 81173681971200 is 217918637118.

81173681971200 is a `hidden beast` number, since 8 + 1 + 1 + 7 + 368 + 1 + 9 + 71 + 200 = 666.

It is a tau number, because it is divible by the number of its divisors (2016).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

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 143 ways as a sum of consecutive naturals, for example, 6541510596 + ... + 6541523004.

Almost surely, 2^{81173681971200} is an apocalyptic number.

81173681971200 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 81173681971200, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (184543171070400).

81173681971200 is an abundant number, since it is smaller than the sum of its proper divisors (287912660169600).

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

81173681971200 is a wasteful number, since it uses less digits than its factorization.

81173681971200 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12487 (or 12439 counting only the distinct ones).

The product of its (nonzero) digits is 1016064, while the sum is 54.

The spelling of 81173681971200 in words is "eighty-one trillion, one hundred seventy-three billion, six hundred eighty-one million, nine hundred seventy-one thousand, two hundred".