81943328320 has 56 divisors (see below), whose sum is σ = 223002921024. Its totient is φ = 28094854656.

The previous prime is 81943328309. The next prime is 81943328339. The reversal of 81943328320 is 2382334918.

It is a tau number, because it is divible by the number of its divisors (56).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18288682 + ... + 18293161.

Almost surely, 2^81943328320 is an apocalyptic number.

81943328320 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81943328320 is an abundant number, since it is smaller than the sum of its proper divisors (141059592704).

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

81943328320 is a wasteful number, since it uses less digits than its factorization.

81943328320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36581867 (or 36581857 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 43.

The spelling of 81943328320 in words is "eighty-one billion, nine hundred forty-three million, three hundred twenty-eight thousand, three hundred twenty".