6659991 has 12 divisors (see below), whose sum is σ = 10360168. Its totient is φ = 4098384.

The previous prime is 6659977. The next prime is 6660011. The reversal of 6659991 is 1999566.

It is not a de Polignac number, because 6659991 - 2¹⁴ = 6643607 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6659921) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 28345 + ... + 28578.

Almost surely, 2^6659991 is an apocalyptic number.

6659991 is a deficient number, since it is larger than the sum of its proper divisors (3700177).

6659991 is a wasteful number, since it uses less digits than its factorization.

6659991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56942 (or 56939 counting only the distinct ones).

The product of its digits is 131220, while the sum is 45.

The square root of 6659991 is about 2580.6958363976. The cubic root of 6659991 is about 188.1443643676.

The spelling of 6659991 in words is "six million, six hundred fifty-nine thousand, nine hundred ninety-one".