644632309 has 2 divisors, whose sum is σ = 644632310. Its totient is φ = 644632308.

The previous prime is 644632301. The next prime is 644632319. The reversal of 644632309 is 903236446.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 406022500 + 238609809 = 20150^2 + 15447^2 .

It is a cyclic number.

It is not a de Polignac number, because 644632309 - 2³ = 644632301 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644632301) 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, 322316154 + 322316155.

It is an arithmetic number, because the mean of its divisors is an integer number (322316155).

Almost surely, 2^644632309 is an apocalyptic number.

It is an amenable number.

644632309 is a deficient number, since it is larger than the sum of its proper divisors (1).

644632309 is an equidigital number, since it uses as much as digits as its factorization.

644632309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 93312, while the sum is 37.

The square root of 644632309 is about 25389.6102569535. The cubic root of 644632309 is about 863.8480479269.

The spelling of 644632309 in words is "six hundred forty-four million, six hundred thirty-two thousand, three hundred nine".