644341549 has 2 divisors, whose sum is σ = 644341550. Its totient is φ = 644341548.

The previous prime is 644341513. The next prime is 644341553. The reversal of 644341549 is 945143446.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 461605225 + 182736324 = 21485^2 + 13518^2 .

It is a cyclic number.

It is not a de Polignac number, because 644341549 - 2⁹ = 644341037 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644341559) 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, 322170774 + 322170775.

It is an arithmetic number, because the mean of its divisors is an integer number (322170775).

Almost surely, 2^644341549 is an apocalyptic number.

It is an amenable number.

644341549 is a deficient number, since it is larger than the sum of its proper divisors (1).

644341549 is an equidigital number, since it uses as much as digits as its factorization.

644341549 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 207360, while the sum is 40.

The square root of 644341549 is about 25383.8836469127. The cubic root of 644341549 is about 863.7181494675.

The spelling of 644341549 in words is "six hundred forty-four million, three hundred forty-one thousand, five hundred forty-nine".