1668791 has 2 divisors, whose sum is σ = 1668792. Its totient is φ = 1668790.

The previous prime is 1668773. The next prime is 1668803. The reversal of 1668791 is 1978661.

It is a strong prime.

It is an emirp because it is prime and its reverse (1978661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1668791 - 2⁶ = 1668727 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1668721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834395 + 834396.

It is an arithmetic number, because the mean of its divisors is an integer number (834396).

2^1668791 is an apocalyptic number.

1668791 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668791 is an equidigital number, since it uses as much as digits as its factorization.

1668791 is an evil number, because the sum of its binary digits is even.

The product of its digits is 18144, while the sum is 38.

The square root of 1668791 is about 1291.8169374954. The cubic root of 1668791 is about 118.6134622762.

The spelling of 1668791 in words is "one million, six hundred sixty-eight thousand, seven hundred ninety-one".