81291703680 has 1536 divisors, whose sum is σ = 348052723200. Its totient is φ = 17915904000.

The previous prime is 81291703663. The next prime is 81291703709. The reversal of 81291703680 is 8630719218.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

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 191 ways as a sum of consecutive naturals, for example, 1332650850 + ... + 1332650910.

It is an arithmetic number, because the mean of its divisors is an integer number (226596825).

Almost surely, 2^81291703680 is an apocalyptic number.

81291703680 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 81291703680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (174026361600).

81291703680 is an abundant number, since it is smaller than the sum of its proper divisors (266761019520).

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

81291703680 is a wasteful number, since it uses less digits than its factorization.

81291703680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 166 (or 142 counting only the distinct ones).

The product of its (nonzero) digits is 145152, while the sum is 45.

The spelling of 81291703680 in words is "eighty-one billion, two hundred ninety-one million, seven hundred three thousand, six hundred eighty".