81765750720 has 448 divisors, whose sum is σ = 276467742720. Its totient is φ = 20432535552.

The previous prime is 81765750709. The next prime is 81765750757. The reversal of 81765750720 is 2705756718.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 81765750720.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 357055566 + ... + 357055794.

Almost surely, 2^81765750720 is an apocalyptic number.

81765750720 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 81765750720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138233871360).

81765750720 is an abundant number, since it is smaller than the sum of its proper divisors (194701992000).

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

81765750720 is a wasteful number, since it uses less digits than its factorization.

81765750720 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 532 (or 522 counting only the distinct ones).

The product of its (nonzero) digits is 823200, while the sum is 48.

The spelling of 81765750720 in words is "eighty-one billion, seven hundred sixty-five million, seven hundred fifty thousand, seven hundred twenty".