666679 has 4 divisors (see below), whose sum is σ = 717976. Its totient is φ = 615384.

The previous prime is 666671. The next prime is 666683. The reversal of 666679 is 976666.

666679 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 976666 = 2 ⋅488333.

It is a cyclic number.

It is not a de Polignac number, because 666679 - 2³ = 666671 is a prime.

It is a Duffinian number.

It is a plaindrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666671) 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, 25629 + ... + 25654.

It is an arithmetic number, because the mean of its divisors is an integer number (179494).

2⁶⁶⁶⁶⁷⁹ is an apocalyptic number.

666679 is a deficient number, since it is larger than the sum of its proper divisors (51297).

666679 is a wasteful number, since it uses less digits than its factorization.

666679 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51296.

The product of its digits is 81648, while the sum is 40.

The square root of 666679 is about 816.5041334862. The cubic root of 666679 is about 87.3585851783.

The spelling of 666679 in words is "six hundred sixty-six thousand, six hundred seventy-nine".