6659986 has 4 divisors (see below), whose sum is σ = 9989982. Its totient is φ = 3329992.

The previous prime is 6659977. The next prime is 6660011. The reversal of 6659986 is 6899566.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 6899566 = 2 ⋅3449783.

It can be written as a sum of positive squares in only one way, i.e., 6125625 + 534361 = 2475^2 + 731^2 .

It is a super-4 number, since 4×6659986⁴ (a number of 28 digits) contains 4444 as substring.

It is an Ulam number.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 1664995 + ... + 1664998.

Almost surely, 2^6659986 is an apocalyptic number.

6659986 is a deficient number, since it is larger than the sum of its proper divisors (3329996).

6659986 is a wasteful number, since it uses less digits than its factorization.

6659986 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3329995.

The product of its digits is 699840, while the sum is 49.

The square root of 6659986 is about 2580.6948676665. The cubic root of 6659986 is about 188.1443172844.

The spelling of 6659986 in words is "six million, six hundred fifty-nine thousand, nine hundred eighty-six".