1666111 has 2 divisors, whose sum is σ = 1666112.
Its totient is φ = 1666110.
The previous prime is 1666081. The next prime is 1666127. The reversal of 1666111 is 1116661.
It is a strong prime.
It is a cyclic number.
It is not a de Polignac number, because 1666111 - 211 = 1664063 is a prime.
It is equal to p125752 and since 1666111 and 125752 have the same sum of digits, it is a Honaker prime.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (1666151) 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 as a sum of consecutive naturals, namely, 833055 + 833056.
It is an arithmetic number, because the mean of its divisors is an integer number (833056).
21666111 is an apocalyptic number.
1666111 is a deficient number, since it is larger than the sum of its proper divisors (1).
1666111 is an equidigital number, since it uses as much as digits as its factorization.
1666111 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 216, while the sum is 22.
The square root of 1666111 is about 1290.7792220206.
The cubic root of 1666111 is about 118.5499323714.
The spelling of 1666111 in words is "one million, six hundred sixty-six thousand, one hundred eleven".