6663609891 has 6 divisors (see below), whose sum is σ = 9625214300. Its totient is φ = 4442406588.

The previous prime is 6663609889. The next prime is 6663609893. The reversal of 6663609891 is 1989063666.

6663609891 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (6663609889) and next prime (6663609893).

It is not a de Polignac number, because 6663609891 - 2¹ = 6663609889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (6663609893) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 370200541 + ... + 370200558.

Almost surely, 2^6663609891 is an apocalyptic number.

6663609891 is a deficient number, since it is larger than the sum of its proper divisors (2961604409).

6663609891 is a wasteful number, since it uses less digits than its factorization.

6663609891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 740401105 (or 740401102 counting only the distinct ones).

The product of its (nonzero) digits is 2519424, while the sum is 54.

The square root of 6663609891 is about 81630.9370949519. The cubic root of 6663609891 is about 1881.7843601828.

The spelling of 6663609891 in words is "six billion, six hundred sixty-three million, six hundred nine thousand, eight hundred ninety-one".