81998956800 has 540 divisors, whose sum is σ = 304718996736. Its totient is φ = 21756211200.

The previous prime is 81998956789. The next prime is 81998956817. The reversal of 81998956800 is 865989918.

It is a tau number, because it is divible by the number of its divisors (540).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 59 ways as a sum of consecutive naturals, for example, 190252585 + ... + 190253015.

Almost surely, 2^81998956800 is an apocalyptic number.

81998956800 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 81998956800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (152359498368).

81998956800 is an abundant number, since it is smaller than the sum of its proper divisors (222720039936).

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

81998956800 is a wasteful number, since it uses less digits than its factorization.

81998956800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 836 (or 808 counting only the distinct ones).

The product of its (nonzero) digits is 11197440, while the sum is 63.

The spelling of 81998956800 in words is "eighty-one billion, nine hundred ninety-eight million, nine hundred fifty-six thousand, eight hundred".