1643445673 has 2 divisors, whose sum is σ = 1643445674. Its totient is φ = 1643445672.

The previous prime is 1643445623. The next prime is 1643445701. The reversal of 1643445673 is 3765443461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1584278809 + 59166864 = 39803^2 + 7692^2 .

It is a cyclic number.

It is not a de Polignac number, because 1643445673 - 2⁹ = 1643445161 is a prime.

It is not a weakly prime, because it can be changed into another prime (1643445623) 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, 821722836 + 821722837.

It is an arithmetic number, because the mean of its divisors is an integer number (821722837).

Almost surely, 2^1643445673 is an apocalyptic number.

It is an amenable number.

1643445673 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643445673 is an equidigital number, since it uses as much as digits as its factorization.

1643445673 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 725760, while the sum is 43.

The square root of 1643445673 is about 40539.4335554901. The cubic root of 1643445673 is about 1180.0990228592.

The spelling of 1643445673 in words is "one billion, six hundred forty-three million, four hundred forty-five thousand, six hundred seventy-three".