681868169 has 2 divisors, whose sum is σ = 681868170. Its totient is φ = 681868168.

The previous prime is 681868141. The next prime is 681868217. The reversal of 681868169 is 961868186.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 502656400 + 179211769 = 22420^2 + 13387^2 .

It is a cyclic number.

It is not a de Polignac number, because 681868169 - 2²⁰ = 680819593 is a prime.

It is a super-2 number, since 2×681868169² = 929888399790825122, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 681868169.

It is not a weakly prime, because it can be changed into another prime (681868129) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 340934084 + 340934085.

It is an arithmetic number, because the mean of its divisors is an integer number (340934085).

Almost surely, 2^681868169 is an apocalyptic number.

It is an amenable number.

681868169 is a deficient number, since it is larger than the sum of its proper divisors (1).

681868169 is an equidigital number, since it uses as much as digits as its factorization.

681868169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 995328, while the sum is 53.

The square root of 681868169 is about 26112.6055574697. The cubic root of 681868169 is about 880.1704942557.

The spelling of 681868169 in words is "six hundred eighty-one million, eight hundred sixty-eight thousand, one hundred sixty-nine".