6686945 has 4 divisors (see below), whose sum is σ = 8024340. Its totient is φ = 5349552.

The previous prime is 6686941. The next prime is 6686947. The reversal of 6686945 is 5496866.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5496866 = 2 ⋅2748433.

It can be written as a sum of positive squares in 2 ways, for example, as 5071504 + 1615441 = 2252^2 + 1271^2 .

It is a cyclic number.

It is not a de Polignac number, because 6686945 - 2² = 6686941 is a prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 6686896 and 6686905.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6686941) 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, 668690 + ... + 668699.

It is an arithmetic number, because the mean of its divisors is an integer number (2006085).

Almost surely, 2^6686945 is an apocalyptic number.

It is an amenable number.

6686945 is a deficient number, since it is larger than the sum of its proper divisors (1337395).

6686945 is a wasteful number, since it uses less digits than its factorization.

6686945 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1337394.

The product of its digits is 311040, while the sum is 44.

The square root of 6686945 is about 2585.9127982204. The cubic root of 6686945 is about 188.3978390431.

The spelling of 6686945 in words is "six million, six hundred eighty-six thousand, nine hundred forty-five".