668525909 has 2 divisors, whose sum is σ = 668525910. Its totient is φ = 668525908.

The previous prime is 668525863. The next prime is 668525959. The reversal of 668525909 is 909525866.

It is an a-pointer prime, because the next prime (668525959) can be obtained adding 668525909 to its sum of digits (50).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 366531025 + 301994884 = 19145^2 + 17378^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-668525909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (668525959) 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, 334262954 + 334262955.

It is an arithmetic number, because the mean of its divisors is an integer number (334262955).

Almost surely, 2^668525909 is an apocalyptic number.

It is an amenable number.

668525909 is a deficient number, since it is larger than the sum of its proper divisors (1).

668525909 is an equidigital number, since it uses as much as digits as its factorization.

668525909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1166400, while the sum is 50.

The square root of 668525909 is about 25855.8679800157. The cubic root of 668525909 is about 874.3918098503.

The spelling of 668525909 in words is "six hundred sixty-eight million, five hundred twenty-five thousand, nine hundred nine".