1666393 has 2 divisors, whose sum is σ = 1666394. Its totient is φ = 1666392.

The previous prime is 1666387. The next prime is 1666397. The reversal of 1666393 is 3936661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 974169 + 692224 = 987^2 + 832^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666393 - 2⁵ = 1666361 is a prime.

1666393 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (1666397) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833196 + 833197.

It is an arithmetic number, because the mean of its divisors is an integer number (833197).

2^1666393 is an apocalyptic number.

It is an amenable number.

1666393 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666393 is an equidigital number, since it uses as much as digits as its factorization.

1666393 is an evil number, because the sum of its binary digits is even.

The product of its digits is 17496, while the sum is 34.

The square root of 1666393 is about 1290.8884537403. Note that the first 3 decimals coincide. The cubic root of 1666393 is about 118.5566204402.

The spelling of 1666393 in words is "one million, six hundred sixty-six thousand, three hundred ninety-three".