666539 has 4 divisors (see below), whose sum is σ = 701640. Its totient is φ = 631440.

The previous prime is 666529. The next prime is 666541. The reversal of 666539 is 935666.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 935666 = 2 ⋅467833.

It is a cyclic number.

It is not a de Polignac number, because 666539 - 2¹² = 662443 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 666499 and 666508.

It is not an unprimeable number, because it can be changed into a prime (666529) 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, 17522 + ... + 17559.

It is an arithmetic number, because the mean of its divisors is an integer number (175410).

2⁶⁶⁶⁵³⁹ is an apocalyptic number.

666539 is a deficient number, since it is larger than the sum of its proper divisors (35101).

666539 is a wasteful number, since it uses less digits than its factorization.

666539 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35100.

The product of its digits is 29160, while the sum is 35.

The square root of 666539 is about 816.4183976369. The cubic root of 666539 is about 87.3524697623.

The spelling of 666539 in words is "six hundred sixty-six thousand, five hundred thirty-nine".