6661813 has 8 divisors (see below), whose sum is σ = 6874200. Its totient is φ = 6451200.

The previous prime is 6661783. The next prime is 6661849. The reversal of 6661813 is 3181666.

It can be written as a sum of positive squares in 4 ways, for example, as 4831204 + 1830609 = 2198^2 + 1353^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 6661813 - 2⁹ = 6661301 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6661873) 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 7 ways as a sum of consecutive naturals, for example, 14613 + ... + 15061.

It is an arithmetic number, because the mean of its divisors is an integer number (859275).

Almost surely, 2^6661813 is an apocalyptic number.

It is an amenable number.

6661813 is a deficient number, since it is larger than the sum of its proper divisors (212387).

6661813 is a wasteful number, since it uses less digits than its factorization.

6661813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 887.

The product of its digits is 5184, while the sum is 31.

The square root of 6661813 is about 2581.0488178258. The cubic root of 6661813 is about 188.1615199352.

The spelling of 6661813 in words is "six million, six hundred sixty-one thousand, eight hundred thirteen".