1668175818121 has 2 divisors, whose sum is σ = 1668175818122. Its totient is φ = 1668175818120.

The previous prime is 1668175818109. The next prime is 1668175818173. The reversal of 1668175818121 is 1218185718661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1418111814025 + 250064004096 = 1190845^2 + 500064^2 .

It is an emirp because it is prime and its reverse (1218185718661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1668175818121 - 2³¹ = 1666028334473 is a prime.

It is not a weakly prime, because it can be changed into another prime (1668175858121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834087909060 + 834087909061.

It is an arithmetic number, because the mean of its divisors is an integer number (834087909061).

Almost surely, 2^{1668175818121} is an apocalyptic number.

It is an amenable number.

1668175818121 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668175818121 is an equidigital number, since it uses as much as digits as its factorization.

1668175818121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1290240, while the sum is 55.

The spelling of 1668175818121 in words is "one trillion, six hundred sixty-eight billion, one hundred seventy-five million, eight hundred eighteen thousand, one hundred twenty-one".