1643443897 has 2 divisors, whose sum is σ = 1643443898. Its totient is φ = 1643443896.

The previous prime is 1643443861. The next prime is 1643443913. The reversal of 1643443897 is 7983443461.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1221921936 + 421521961 = 34956^2 + 20531^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1643443897 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1643443897.

It is not a weakly prime, because it can be changed into another prime (1643443847) 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, 821721948 + 821721949.

It is an arithmetic number, because the mean of its divisors is an integer number (821721949).

Almost surely, 2^1643443897 is an apocalyptic number.

It is an amenable number.

1643443897 is a deficient number, since it is larger than the sum of its proper divisors (1).

1643443897 is an equidigital number, since it uses as much as digits as its factorization.

1643443897 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1741824, while the sum is 49.

The square root of 1643443897 is about 40539.4116508861. The cubic root of 1643443897 is about 1180.0985977652.

The spelling of 1643443897 in words is "one billion, six hundred forty-three million, four hundred forty-three thousand, eight hundred ninety-seven".