1666820317 has 2 divisors, whose sum is σ = 1666820318. Its totient is φ = 1666820316.

The previous prime is 1666820299. The next prime is 1666820321. The reversal of 1666820317 is 7130286661.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1486025401 + 180794916 = 38549^2 + 13446^2 .

It is an emirp because it is prime and its reverse (7130286661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666820317 - 2¹¹ = 1666818269 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1666820317.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666820117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833410158 + 833410159.

It is an arithmetic number, because the mean of its divisors is an integer number (833410159).

Almost surely, 2^1666820317 is an apocalyptic number.

It is an amenable number.

1666820317 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666820317 is an equidigital number, since it uses as much as digits as its factorization.

1666820317 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 72576, while the sum is 40.

The square root of 1666820317 is about 40826.7108275942. The cubic root of 1666820317 is about 1185.6675348999.

The spelling of 1666820317 in words is "one billion, six hundred sixty-six million, eight hundred twenty thousand, three hundred seventeen".