6687409 has 4 divisors (see below), whose sum is σ = 7080804. Its totient is φ = 6294016.

The previous prime is 6687391. The next prime is 6687427. The reversal of 6687409 is 9047866.

It is a semiprime because it is the product of two primes.

It is an interprime number because it is at equal distance from previous prime (6687391) and next prime (6687427).

It can be written as a sum of positive squares in 2 ways, for example, as 5049009 + 1638400 = 2247^2 + 1280^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-6687409 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6687209) 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, 196672 + ... + 196705.

It is an arithmetic number, because the mean of its divisors is an integer number (1770201).

Almost surely, 2^6687409 is an apocalyptic number.

It is an amenable number.

6687409 is a deficient number, since it is larger than the sum of its proper divisors (393395).

6687409 is a wasteful number, since it uses less digits than its factorization.

6687409 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 393394.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 6687409 is about 2586.0025135332. The cubic root of 6687409 is about 188.4021965176.

The spelling of 6687409 in words is "six million, six hundred eighty-seven thousand, four hundred nine".