665555 has 8 divisors (see below), whose sum is σ = 871344. Its totient is φ = 484000.

The previous prime is 665549. The next prime is 665557. The reversal of 665555 is 555566.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 665555 - 2⁸ = 665299 is a prime.

It is a Duffinian number.

It is a plaindrome in base 14.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

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 665555.

It is not an unprimeable number, because it can be changed into a prime (665557) 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 7 ways as a sum of consecutive naturals, for example, 5996 + ... + 6105.

It is an arithmetic number, because the mean of its divisors is an integer number (108918).

It is the magic constant of a 110 × 110 magic square.

2⁶⁶⁵⁵⁵⁵ is an apocalyptic number.

665555 is a deficient number, since it is larger than the sum of its proper divisors (205789).

665555 is a wasteful number, since it uses less digits than its factorization.

665555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12117.

The product of its digits is 22500, while the sum is 32.

The square root of 665555 is about 815.8155428772. The cubic root of 665555 is about 87.3094629451.

It can be divided in two parts, 6655 and 55, that multiplied together give a square (366025 = 605²).

The spelling of 665555 in words is "six hundred sixty-five thousand, five hundred fifty-five".