643161109 has 2 divisors, whose sum is σ = 643161110. Its totient is φ = 643161108.

The previous prime is 643161067. The next prime is 643161139. The reversal of 643161109 is 901161346.

643161109 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 513702225 + 129458884 = 22665^2 + 11378^2 .

It is a cyclic number.

It is not a de Polignac number, because 643161109 - 2⁷ = 643160981 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643161139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321580554 + 321580555.

It is an arithmetic number, because the mean of its divisors is an integer number (321580555).

Almost surely, 2^643161109 is an apocalyptic number.

It is an amenable number.

643161109 is a deficient number, since it is larger than the sum of its proper divisors (1).

643161109 is an equidigital number, since it uses as much as digits as its factorization.

643161109 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3888, while the sum is 31.

The square root of 643161109 is about 25360.6212266182. The cubic root of 643161109 is about 863.1903803531.

The spelling of 643161109 in words is "six hundred forty-three million, one hundred sixty-one thousand, one hundred nine".