1666412786501 has 2 divisors, whose sum is σ = 1666412786502. Its totient is φ = 1666412786500.

The previous prime is 1666412786497. The next prime is 1666412786509. The reversal of 1666412786501 is 1056872146661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1363175337601 + 303237448900 = 1167551^2 + 550670^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666412786501 - 2² = 1666412786497 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 (1666412786509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833206393250 + 833206393251.

It is an arithmetic number, because the mean of its divisors is an integer number (833206393251).

Almost surely, 2^{1666412786501} is an apocalyptic number.

It is an amenable number.

1666412786501 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666412786501 is an equidigital number, since it uses as much as digits as its factorization.

1666412786501 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2903040, while the sum is 53.

The spelling of 1666412786501 in words is "one trillion, six hundred sixty-six billion, four hundred twelve million, seven hundred eighty-six thousand, five hundred one".