645122609 has 2 divisors, whose sum is σ = 645122610. Its totient is φ = 645122608.

The previous prime is 645122567. The next prime is 645122627. The reversal of 645122609 is 906221546.

It is a happy number.

645122609 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 537544225 + 107578384 = 23185^2 + 10372^2 .

It is a cyclic number.

It is not a de Polignac number, because 645122609 - 2¹⁶ = 645057073 is a prime.

It is not a weakly prime, because it can be changed into another prime (645122629) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 322561304 + 322561305.

It is an arithmetic number, because the mean of its divisors is an integer number (322561305).

Almost surely, 2^645122609 is an apocalyptic number.

It is an amenable number.

645122609 is a deficient number, since it is larger than the sum of its proper divisors (1).

645122609 is an equidigital number, since it uses as much as digits as its factorization.

645122609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 25920, while the sum is 35.

The square root of 645122609 is about 25399.2639460280. The cubic root of 645122609 is about 864.0670034236.

The spelling of 645122609 in words is "six hundred forty-five million, one hundred twenty-two thousand, six hundred nine".