643304161 has 2 divisors, whose sum is σ = 643304162. Its totient is φ = 643304160.

The previous prime is 643304159. The next prime is 643304171. The reversal of 643304161 is 161403346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 472845025 + 170459136 = 21745^2 + 13056^2 .

It is a cyclic number.

It is not a de Polignac number, because 643304161 - 2¹ = 643304159 is a prime.

Together with 643304159, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (643304171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321652080 + 321652081.

It is an arithmetic number, because the mean of its divisors is an integer number (321652081).

Almost surely, 2^643304161 is an apocalyptic number.

It is an amenable number.

643304161 is a deficient number, since it is larger than the sum of its proper divisors (1).

643304161 is an equidigital number, since it uses as much as digits as its factorization.

643304161 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 28.

The square root of 643304161 is about 25363.4414265888. The cubic root of 643304161 is about 863.2543725912.

The spelling of 643304161 in words is "six hundred forty-three million, three hundred four thousand, one hundred sixty-one".