81681600000 has 1920 divisors, whose sum is σ = 386669251584. Its totient is φ = 14745600000.

The previous prime is 81681599977. The next prime is 81681600059. The reversal of 81681600000 is 618618.

It is a tau number, because it is divible by the number of its divisors (1920).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 4804799992 + ... + 4804800008.

Almost surely, 2^81681600000 is an apocalyptic number.

81681600000 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 81681600000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (193334625792).

81681600000 is an abundant number, since it is smaller than the sum of its proper divisors (304987651584).

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

81681600000 is a wasteful number, since it uses less digits than its factorization.

81681600000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 94 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 30.

The spelling of 81681600000 in words is "eighty-one billion, six hundred eighty-one million, six hundred thousand".