665487209 has 2 divisors, whose sum is σ = 665487210. Its totient is φ = 665487208.

The previous prime is 665487181. The next prime is 665487233. The reversal of 665487209 is 902784566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 402885184 + 262602025 = 20072^2 + 16205^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665487209 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (665487409) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332743604 + 332743605.

It is an arithmetic number, because the mean of its divisors is an integer number (332743605).

Almost surely, 2^665487209 is an apocalyptic number.

It is an amenable number.

665487209 is a deficient number, since it is larger than the sum of its proper divisors (1).

665487209 is an equidigital number, since it uses as much as digits as its factorization.

665487209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 725760, while the sum is 47.

The square root of 665487209 is about 25797.0387641683. The cubic root of 665487209 is about 873.0649850351.

The spelling of 665487209 in words is "six hundred sixty-five million, four hundred eighty-seven thousand, two hundred nine".