681667766185 has 24 divisors (see below), whose sum is σ = 951821287560. Its totient is φ = 467297316864.

The previous prime is 681667766183. The next prime is 681667766191. The reversal of 681667766185 is 581667766186.

It can be written as a sum of positive squares in 4 ways, for example, as 28855477161 + 652812289024 = 169869^2 + 807968^2 .

It is not a de Polignac number, because 681667766185 - 2¹ = 681667766183 is a prime.

It is a Smith number, since the sum of its digits (67) coincides with the sum of the digits of its prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 681667766185.

It is not an unprimeable number, because it can be changed into a prime (681667766183) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 480361 + ... + 1262569.

It is an arithmetic number, because the mean of its divisors is an integer number (39659220315).

Almost surely, 2^681667766185 is an apocalyptic number.

It is an amenable number.

681667766185 is a deficient number, since it is larger than the sum of its proper divisors (270153521375).

681667766185 is a wasteful number, since it uses less digits than its factorization.

681667766185 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 785785 (or 785778 counting only the distinct ones).

The product of its digits is 121927680, while the sum is 67.

Subtracting from 681667766185 its reverse (581667766186), we obtain a palindrome (99999999999).

The spelling of 681667766185 in words is "six hundred eighty-one billion, six hundred sixty-seven million, seven hundred sixty-six thousand, one hundred eighty-five".