666599 has 2 divisors, whose sum is σ = 666600. Its totient is φ = 666598.

The previous prime is 666559. The next prime is 666607. The reversal of 666599 is 995666.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666599 is a prime.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 666599.

It is not a weakly prime, because it can be changed into another prime (666529) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 333299 + 333300.

It is an arithmetic number, because the mean of its divisors is an integer number (333300).

2⁶⁶⁶⁵⁹⁹ is an apocalyptic number.

666599 is a deficient number, since it is larger than the sum of its proper divisors (1).

666599 is an equidigital number, since it uses as much as digits as its factorization.

666599 is an evil number, because the sum of its binary digits is even.

The product of its digits is 87480, while the sum is 41.

The square root of 666599 is about 816.4551426747. The cubic root of 666599 is about 87.3550907597.

It can be divided in two parts, 66 and 6599, that multiplied together give a palindrome (435534).

The spelling of 666599 in words is "six hundred sixty-six thousand, five hundred ninety-nine".