665659 has 2 divisors, whose sum is σ = 665660. Its totient is φ = 665658.

The previous prime is 665633. The next prime is 665677. The reversal of 665659 is 956566.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 665659 - 2¹⁹ = 141371 is a prime.

It is not a weakly prime, because it can be changed into another prime (665629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332829 + 332830.

It is an arithmetic number, because the mean of its divisors is an integer number (332830).

2⁶⁶⁵⁶⁵⁹ is an apocalyptic number.

665659 is a deficient number, since it is larger than the sum of its proper divisors (1).

665659 is an equidigital number, since it uses as much as digits as its factorization.

665659 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48600, while the sum is 37.

The square root of 665659 is about 815.8792802860. The cubic root of 665659 is about 87.3140103836.

The spelling of 665659 in words is "six hundred sixty-five thousand, six hundred fifty-nine".