6681509 has 4 divisors (see below), whose sum is σ = 6688716. Its totient is φ = 6674304.

The previous prime is 6681491. The next prime is 6681511. The reversal of 6681509 is 9051866.

6681509 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 5536609 + 1144900 = 2353^2 + 1070^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6681509 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6681529) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1964 + ... + 4149.

It is an arithmetic number, because the mean of its divisors is an integer number (1672179).

Almost surely, 2^6681509 is an apocalyptic number.

It is an amenable number.

6681509 is a deficient number, since it is larger than the sum of its proper divisors (7207).

6681509 is a wasteful number, since it uses less digits than its factorization.

6681509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7206.

The product of its (nonzero) digits is 12960, while the sum is 35.

The square root of 6681509 is about 2584.8615049940. The cubic root of 6681509 is about 188.3467739557.

The spelling of 6681509 in words is "six million, six hundred eighty-one thousand, five hundred nine".