81789765120 has 1920 divisors, whose sum is σ = 376175923200. Its totient is φ = 16721510400.

The previous prime is 81789765119. The next prime is 81789765137. The reversal of 81789765120 is 2156798718.

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

It is a super-2 number, since 2×81789765120² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

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, 1994872300 + ... + 1994872340.

It is an arithmetic number, because the mean of its divisors is an integer number (195924960).

Almost surely, 2^81789765120 is an apocalyptic number.

81789765120 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 81789765120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (188087961600).

81789765120 is an abundant number, since it is smaller than the sum of its proper divisors (294386158080).

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

81789765120 is a wasteful number, since it uses less digits than its factorization.

81789765120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 137 (or 108 counting only the distinct ones).

The product of its (nonzero) digits is 1693440, while the sum is 54.

The spelling of 81789765120 in words is "eighty-one billion, seven hundred eighty-nine million, seven hundred sixty-five thousand, one hundred twenty".