1666104456217 has 2 divisors, whose sum is σ = 1666104456218. Its totient is φ = 1666104456216.

The previous prime is 1666104456139. The next prime is 1666104456251. The reversal of 1666104456217 is 7126544016661.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1664561852041 + 1542604176 = 1290179^2 + 39276^2 .

It is an emirp because it is prime and its reverse (7126544016661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666104456217 - 2³⁵ = 1631744717849 is a prime.

It is a super-2 number, since 2×1666104456217² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1666104456917) 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, 833052228108 + 833052228109.

It is an arithmetic number, because the mean of its divisors is an integer number (833052228109).

Almost surely, 2^{1666104456217} is an apocalyptic number.

It is an amenable number.

1666104456217 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666104456217 is an equidigital number, since it uses as much as digits as its factorization.

1666104456217 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1451520, while the sum is 49.

The spelling of 1666104456217 in words is "one trillion, six hundred sixty-six billion, one hundred four million, four hundred fifty-six thousand, two hundred seventeen".