666556617 has 8 divisors (see below), whose sum is σ = 888904096. Its totient is φ = 444290112.

The previous prime is 666556543. The next prime is 666556643. The reversal of 666556617 is 716655666.

It is a happy number.

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

It is not a de Polignac number, because 666556617 - 2⁷ = 666556489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666556817) 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 7 ways as a sum of consecutive naturals, for example, 2673 + ... + 36609.

It is an arithmetic number, because the mean of its divisors is an integer number (111113012).

Almost surely, 2^666556617 is an apocalyptic number.

It is an amenable number.

666556617 is a deficient number, since it is larger than the sum of its proper divisors (222347479).

666556617 is a wasteful number, since it uses less digits than its factorization.

666556617 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40487.

The product of its digits is 1360800, while the sum is 48.

The square root of 666556617 is about 25817.7577841299. The cubic root of 666556617 is about 873.5323934716.

The spelling of 666556617 in words is "six hundred sixty-six million, five hundred fifty-six thousand, six hundred seventeen".