1668594958661 has 2 divisors, whose sum is σ = 1668594958662. Its totient is φ = 1668594958660.

The previous prime is 1668594958633. The next prime is 1668594958669.

1668594958661 is nontrivially palindromic in base 10.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1667985165025 + 609793636 = 1291505^2 + 24694^2 .

It is a palprime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1668594958661 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1668594958669) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834297479330 + 834297479331.

It is an arithmetic number, because the mean of its divisors is an integer number (834297479331).

Almost surely, 2^{1668594958661} is an apocalyptic number.

It is an amenable number.

1668594958661 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668594958661 is an equidigital number, since it uses as much as digits as its factorization.

1668594958661 is an evil number, because the sum of its binary digits is even.

The product of its digits is 671846400, while the sum is 74.

The spelling of 1668594958661 in words is "one trillion, six hundred sixty-eight billion, five hundred ninety-four million, nine hundred fifty-eight thousand, six hundred sixty-one".