6681689 has 6 divisors (see below), whose sum is σ = 7772634. Its totient is φ = 5727120.

The previous prime is 6681683. The next prime is 6681721. The reversal of 6681689 is 9861866.

6681689 = 345² + 346² + ... + 393².

It can be written as a sum of positive squares in only one way, i.e., 6528025 + 153664 = 2555^2 + 392^2 .

It is a de Polignac number, because none of the positive numbers 2^k-6681689 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (6681683) 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 5 ways as a sum of consecutive naturals, for example, 68132 + ... + 68229.

It is an arithmetic number, because the mean of its divisors is an integer number (1295439).

Almost surely, 2^6681689 is an apocalyptic number.

It is an amenable number.

6681689 is a deficient number, since it is larger than the sum of its proper divisors (1090945).

6681689 is a wasteful number, since it uses less digits than its factorization.

6681689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136375 (or 136368 counting only the distinct ones).

The product of its digits is 124416, while the sum is 44.

The square root of 6681689 is about 2584.8963228725. The cubic root of 6681689 is about 188.3484652959.

The spelling of 6681689 in words is "six million, six hundred eighty-one thousand, six hundred eighty-nine".