666817 has 4 divisors (see below), whose sum is σ = 669060. Its totient is φ = 664576.

The previous prime is 666811. The next prime is 666821. The reversal of 666817 is 718666.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 295936 + 370881 = 544^2 + 609^2 .

It is a cyclic number.

It is not a de Polignac number, because 666817 - 2¹⁹ = 142529 is a prime.

It is a super-2 number, since 2×666817² = 889289822978, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 592 + ... + 1297.

It is an arithmetic number, because the mean of its divisors is an integer number (167265).

2⁶⁶⁶⁸¹⁷ is an apocalyptic number.

It is an amenable number.

666817 is a deficient number, since it is larger than the sum of its proper divisors (2243).

666817 is a wasteful number, since it uses less digits than its factorization.

666817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2242.

The product of its digits is 12096, while the sum is 34.

The square root of 666817 is about 816.5886357279. The cubic root of 666817 is about 87.3646123933.

The spelling of 666817 in words is "six hundred sixty-six thousand, eight hundred seventeen".