644773699 has 2 divisors, whose sum is σ = 644773700. Its totient is φ = 644773698.

The previous prime is 644773687. The next prime is 644773781. The reversal of 644773699 is 996377446.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644773699 is a prime.

It is not a weakly prime, because it can be changed into another prime (644773639) 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, 322386849 + 322386850.

It is an arithmetic number, because the mean of its divisors is an integer number (322386850).

Almost surely, 2^644773699 is an apocalyptic number.

644773699 is a deficient number, since it is larger than the sum of its proper divisors (1).

644773699 is an equidigital number, since it uses as much as digits as its factorization.

644773699 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6858432, while the sum is 55.

The square root of 644773699 is about 25392.3945109554. The cubic root of 644773699 is about 863.9112004895.

The spelling of 644773699 in words is "six hundred forty-four million, seven hundred seventy-three thousand, six hundred ninety-nine".