6646681 has 4 divisors (see below), whose sum is σ = 6659172. Its totient is φ = 6634192.

The previous prime is 6646669. The next prime is 6646687. The reversal of 6646681 is 1866466.

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

It can be written as a sum of positive squares in 2 ways, for example, as 2975625 + 3671056 = 1725^2 + 1916^2 .

It is a cyclic number.

It is not a de Polignac number, because 6646681 - 2¹⁵ = 6613913 is a prime.

It is a super-2 number, since 2×6646681² = 88356736631522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6646681.

It is not an unprimeable number, because it can be changed into a prime (6646687) 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 3 ways as a sum of consecutive naturals, for example, 5410 + ... + 6523.

It is an arithmetic number, because the mean of its divisors is an integer number (1664793).

Almost surely, 2^6646681 is an apocalyptic number.

It is an amenable number.

6646681 is a deficient number, since it is larger than the sum of its proper divisors (12491).

6646681 is a wasteful number, since it uses less digits than its factorization.

6646681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12490.

The product of its digits is 41472, while the sum is 37.

The square root of 6646681 is about 2578.1157848320. The cubic root of 6646681 is about 188.0189452011.

The spelling of 6646681 in words is "six million, six hundred forty-six thousand, six hundred eighty-one".