81995663836800 has 384 divisors, whose sum is σ = 342950120323200. Its totient is φ = 18741865881600.

The previous prime is 81995663836769. The next prime is 81995663836847. The reversal of 81995663836800 is 863836659918.

81995663836800 is a `hidden beast` number, since 8 + 199 + 56 + 6 + 383 + 6 + 8 + 0 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (384).

It is a super-2 number, since 2×81995663836800² (a number of 29 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 67182621 + ... + 68392220.

It is an arithmetic number, because the mean of its divisors is an integer number (893099271675).

Almost surely, 2^{81995663836800} is an apocalyptic number.

81995663836800 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81995663836800 is an abundant number, since it is smaller than the sum of its proper divisors (260954456486400).

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

81995663836800 is a wasteful number, since it uses less digits than its factorization.

81995663836800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135574881 (or 135574858 counting only the distinct ones).

The product of its (nonzero) digits is 403107840, while the sum is 72.

The spelling of 81995663836800 in words is "eighty-one trillion, nine hundred ninety-five billion, six hundred sixty-three million, eight hundred thirty-six thousand, eight hundred".