81967551165 has 48 divisors (see below), whose sum is σ = 145587602160. Its totient is φ = 42636533760.

The previous prime is 81967551163. The next prime is 81967551221. The reversal of 81967551165 is 56115576918.

81967551165 is a `hidden beast` number, since 8 + 1 + 9 + 67 + 5 + 511 + 65 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 16491953241 + 65475597924 = 128421^2 + 255882^2 .

It is not a de Polignac number, because 81967551165 - 2¹ = 81967551163 is a prime.

It is a hoax number, since the sum of its digits (54) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81967551163) 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 47 ways as a sum of consecutive naturals, for example, 9429141 + ... + 9437829.

It is an arithmetic number, because the mean of its divisors is an integer number (3033075045).

Almost surely, 2^81967551165 is an apocalyptic number.

It is an amenable number.

81967551165 is a deficient number, since it is larger than the sum of its proper divisors (63620050995).

81967551165 is a wasteful number, since it uses less digits than its factorization.

81967551165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13854 (or 13851 counting only the distinct ones).

The product of its digits is 2268000, while the sum is 54.

The spelling of 81967551165 in words is "eighty-one billion, nine hundred sixty-seven million, five hundred fifty-one thousand, one hundred sixty-five".