775666609 has 2 divisors, whose sum is σ = 775666610. Its totient is φ = 775666608.

The previous prime is 775666543. The next prime is 775666649. The reversal of 775666609 is 906666577.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 770617600 + 5049009 = 27760^2 + 2247^2 .

It is an emirp because it is prime and its reverse (906666577) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 775666609 - 2¹⁵ = 775633841 is a prime.

It is not a weakly prime, because it can be changed into another prime (775666649) 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, 387833304 + 387833305.

It is an arithmetic number, because the mean of its divisors is an integer number (387833305).

Almost surely, 2^775666609 is an apocalyptic number.

It is an amenable number.

775666609 is a deficient number, since it is larger than the sum of its proper divisors (1).

775666609 is an equidigital number, since it uses as much as digits as its factorization.

775666609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2857680, while the sum is 52.

The square root of 775666609 is about 27850.7918917937. The cubic root of 775666609 is about 918.8085589096.

The spelling of 775666609 in words is "seven hundred seventy-five million, six hundred sixty-six thousand, six hundred nine".