81720511488 has 1188 divisors, whose sum is σ = 323630208720. Its totient is φ = 19415531520.

The previous prime is 81720511463. The next prime is 81720511519. The reversal of 81720511488 is 88411502718.

It is an unprimeable number.

It is a polite number, since it can be written in 107 ways as a sum of consecutive naturals, for example, 2817948658 + ... + 2817948686.

Almost surely, 2^81720511488 is an apocalyptic number.

81720511488 is a gapful number since it is divisible by the number (88) 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 81720511488, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (161815104360).

81720511488 is an abundant number, since it is smaller than the sum of its proper divisors (241909697232).

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

81720511488 is a wasteful number, since it uses less digits than its factorization.

81720511488 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 122 (or 71 counting only the distinct ones).

The product of its (nonzero) digits is 143360, while the sum is 45.

The spelling of 81720511488 in words is "eighty-one billion, seven hundred twenty million, five hundred eleven thousand, four hundred eighty-eight".