666355 has 4 divisors (see below), whose sum is σ = 799632. Its totient is φ = 533080.

The previous prime is 666353. The next prime is 666403. The reversal of 666355 is 553666.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 553666 = 2 ⋅276833.

It is not a de Polignac number, because 666355 - 2¹ = 666353 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666353) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 66631 + ... + 66640.

It is an arithmetic number, because the mean of its divisors is an integer number (199908).

2⁶⁶⁶³⁵⁵ is an apocalyptic number.

666355 is a deficient number, since it is larger than the sum of its proper divisors (133277).

666355 is a wasteful number, since it uses less digits than its factorization.

666355 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 133276.

The product of its digits is 16200, while the sum is 31.

The square root of 666355 is about 816.3057025404. The cubic root of 666355 is about 87.3444310561.

The spelling of 666355 in words is "six hundred sixty-six thousand, three hundred fifty-five".