1666939 has 2 divisors, whose sum is σ = 1666940. Its totient is φ = 1666938.

The previous prime is 1666933. The next prime is 1666943. The reversal of 1666939 is 9396661.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1666939 - 2⁷ = 1666811 is a prime.

It is not a weakly prime, because it can be changed into another prime (1666933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833469 + 833470.

It is an arithmetic number, because the mean of its divisors is an integer number (833470).

2^1666939 is an apocalyptic number.

1666939 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666939 is an equidigital number, since it uses as much as digits as its factorization.

1666939 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 52488, while the sum is 40.

The square root of 1666939 is about 1291.0999186740. The cubic root of 1666939 is about 118.5695675354.

The spelling of 1666939 in words is "one million, six hundred sixty-six thousand, nine hundred thirty-nine".