666111 has 16 divisors (see below), whose sum is σ = 968544. Its totient is φ = 405504.

The previous prime is 666109. The next prime is 666119. The reversal of 666111 is 111666.

It is not a de Polignac number, because 666111 - 2¹ = 666109 is a prime.

666111 is a lucky number.

It is a nialpdrome in base 10.

It is a zygodrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666119) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1711 + ... + 2063.

It is an arithmetic number, because the mean of its divisors is an integer number (60534).

2⁶⁶⁶¹¹¹ is an apocalyptic number.

666111 is a deficient number, since it is larger than the sum of its proper divisors (302433).

666111 is a wasteful number, since it uses less digits than its factorization.

666111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 410.

The product of its digits is 216, while the sum is 21.

The square root of 666111 is about 816.1562350433. The cubic root of 666111 is about 87.3337687500. Note that the first 3 decimals are identical.

Adding to 666111 its reverse (111666), we get a palindrome (777777).

It can be divided in two parts, 666 and 111, that added together give a palindrome (777).

The spelling of 666111 in words is "six hundred sixty-six thousand, one hundred eleven".