681366609 has 81 divisors (see below), whose sum is σ = 1269658299. Its totient is φ = 350824320.

The previous prime is 681366599. The next prime is 681366611. The reversal of 681366609 is 906663186.

The square root of 681366609 is 26103.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 12006225 + 669360384 = 3465^2 + 25872^2 .

It is not a de Polignac number, because 681366609 - 2¹⁷ = 681235537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (681366109) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 6029737 + ... + 6029849.

Almost surely, 2^681366609 is an apocalyptic number.

681366609 is the 26103-rd square number.

681366609 is the 13052-nd centered octagonal number.

It is an amenable number.

681366609 is a deficient number, since it is larger than the sum of its proper divisors (588291690).

681366609 is a wasteful number, since it uses less digits than its factorization.

681366609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 268 (or 134 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 45.

The cubic root of 681366609 is about 879.9546330779.

The spelling of 681366609 in words is "six hundred eighty-one million, three hundred sixty-six thousand, six hundred nine".