645033209 has 2 divisors, whose sum is σ = 645033210. Its totient is φ = 645033208.

The previous prime is 645033203. The next prime is 645033241. The reversal of 645033209 is 902330546.

It is an a-pointer prime, because the next prime (645033241) can be obtained adding 645033209 to its sum of digits (32).

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 645007609 + 25600 = 25397^2 + 160^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-645033209 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (645033203) 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, 322516604 + 322516605.

It is an arithmetic number, because the mean of its divisors is an integer number (322516605).

Almost surely, 2^645033209 is an apocalyptic number.

It is an amenable number.

645033209 is a deficient number, since it is larger than the sum of its proper divisors (1).

645033209 is an equidigital number, since it uses as much as digits as its factorization.

645033209 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 19440, while the sum is 32.

The square root of 645033209 is about 25397.5039915343. The cubic root of 645033209 is about 864.0270879317.

The spelling of 645033209 in words is "six hundred forty-five million, thirty-three thousand, two hundred nine".