644544763 has 2 divisors, whose sum is σ = 644544764. Its totient is φ = 644544762.

The previous prime is 644544751. The next prime is 644544799. The reversal of 644544763 is 367445446.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 644544763 - 2¹⁷ = 644413691 is a prime.

It is not a weakly prime, because it can be changed into another prime (644544743) 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, 322272381 + 322272382.

It is an arithmetic number, because the mean of its divisors is an integer number (322272382).

Almost surely, 2^644544763 is an apocalyptic number.

644544763 is a deficient number, since it is larger than the sum of its proper divisors (1).

644544763 is an equidigital number, since it uses as much as digits as its factorization.

644544763 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 967680, while the sum is 43.

The square root of 644544763 is about 25387.8861467433. The cubic root of 644544763 is about 863.8089404316.

The spelling of 644544763 in words is "six hundred forty-four million, five hundred forty-four thousand, seven hundred sixty-three".