645464009 has 2 divisors, whose sum is σ = 645464010. Its totient is φ = 645464008.

The previous prime is 645464003. The next prime is 645464011. The reversal of 645464009 is 900464546.

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., 594384400 + 51079609 = 24380^2 + 7147^2 .

It is a cyclic number.

It is not a de Polignac number, because 645464009 - 2⁴ = 645463993 is a prime.

Together with 645464011, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (645464003) 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, 322732004 + 322732005.

It is an arithmetic number, because the mean of its divisors is an integer number (322732005).

Almost surely, 2^645464009 is an apocalyptic number.

It is an amenable number.

645464009 is a deficient number, since it is larger than the sum of its proper divisors (1).

645464009 is an equidigital number, since it uses as much as digits as its factorization.

645464009 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 103680, while the sum is 38.

The square root of 645464009 is about 25405.9837243119. The cubic root of 645464009 is about 864.2193984615.

The spelling of 645464009 in words is "six hundred forty-five million, four hundred sixty-four thousand, nine".