1668418516649 has 2 divisors, whose sum is σ = 1668418516650. Its totient is φ = 1668418516648.

The previous prime is 1668418516627. The next prime is 1668418516727. The reversal of 1668418516649 is 9466158148661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 902737515625 + 765681001024 = 950125^2 + 875032^2 .

It is an emirp because it is prime and its reverse (9466158148661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1668418516649 - 2⁸ = 1668418516393 is a prime.

It is not a weakly prime, because it can be changed into another prime (1668418518649) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 834209258324 + 834209258325.

It is an arithmetic number, because the mean of its divisors is an integer number (834209258325).

Almost surely, 2^{1668418516649} is an apocalyptic number.

It is an amenable number.

1668418516649 is a deficient number, since it is larger than the sum of its proper divisors (1).

1668418516649 is an equidigital number, since it uses as much as digits as its factorization.

1668418516649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 59719680, while the sum is 65.

The spelling of 1668418516649 in words is "one trillion, six hundred sixty-eight billion, four hundred eighteen million, five hundred sixteen thousand, six hundred forty-nine".