81767865312 has 384 divisors, whose sum is σ = 278198323200. Its totient is φ = 22883586048.

The previous prime is 81767865287. The next prime is 81767865313. The reversal of 81767865312 is 21356876718.

It is a happy number.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81767865313) by changing a digit.

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 63 ways as a sum of consecutive naturals, for example, 73730614 + ... + 73731722.

It is an arithmetic number, because the mean of its divisors is an integer number (724474800).

Almost surely, 2^81767865312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81767865312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (139099161600).

81767865312 is an abundant number, since it is smaller than the sum of its proper divisors (196430457888).

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

81767865312 is a wasteful number, since it uses less digits than its factorization.

81767865312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1375 (or 1361 counting only the distinct ones).

The product of its digits is 3386880, while the sum is 54.

The spelling of 81767865312 in words is "eighty-one billion, seven hundred sixty-seven million, eight hundred sixty-five thousand, three hundred twelve".