1666213 has 2 divisors, whose sum is σ = 1666214. Its totient is φ = 1666212.

The previous prime is 1666211. The next prime is 1666237. The reversal of 1666213 is 3126661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1520289 + 145924 = 1233^2 + 382^2 .

It is an emirp because it is prime and its reverse (3126661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666213 - 2¹ = 1666211 is a prime.

It is a super-2 number, since 2×1666213² = 5552531522738, which contains 22 as substring.

Together with 1666211, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666211) 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 as a sum of consecutive naturals, namely, 833106 + 833107.

It is an arithmetic number, because the mean of its divisors is an integer number (833107).

2^1666213 is an apocalyptic number.

It is an amenable number.

1666213 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666213 is an equidigital number, since it uses as much as digits as its factorization.

1666213 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1296, while the sum is 25.

The square root of 1666213 is about 1290.8187324330. The cubic root of 1666213 is about 118.5523515473.

The spelling of 1666213 in words is "one million, six hundred sixty-six thousand, two hundred thirteen".