666655 has 32 divisors (see below), whose sum is σ = 995328. Its totient is φ = 422400.

The previous prime is 666649. The next prime is 666667. The reversal of 666655 is 556666.

666655 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 666655 - 2³ = 666647 is a prime.

It is a Duffinian number.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 666655.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21490 + ... + 21520.

It is an arithmetic number, because the mean of its divisors is an integer number (31104).

2⁶⁶⁶⁶⁵⁵ is an apocalyptic number.

666655 is a deficient number, since it is larger than the sum of its proper divisors (328673).

666655 is a wasteful number, since it uses less digits than its factorization.

666655 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 87.

The product of its digits is 32400, while the sum is 34.

The square root of 666655 is about 816.4894365514. The cubic root of 666655 is about 87.3575368821.

The spelling of 666655 in words is "six hundred sixty-six thousand, six hundred fifty-five".