644539607 has 2 divisors, whose sum is σ = 644539608. Its totient is φ = 644539606.

The previous prime is 644539589. The next prime is 644539663. The reversal of 644539607 is 706935446.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644539607 - 2⁶ = 644539543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (644539697) 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, 322269803 + 322269804.

It is an arithmetic number, because the mean of its divisors is an integer number (322269804).

Almost surely, 2^644539607 is an apocalyptic number.

644539607 is a deficient number, since it is larger than the sum of its proper divisors (1).

644539607 is an equidigital number, since it uses as much as digits as its factorization.

644539607 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 544320, while the sum is 44.

The square root of 644539607 is about 25387.7846020483. The cubic root of 644539607 is about 863.8066370949.

The spelling of 644539607 in words is "six hundred forty-four million, five hundred thirty-nine thousand, six hundred seven".