643728611 has 2 divisors, whose sum is σ = 643728612. Its totient is φ = 643728610.

The previous prime is 643728601. The next prime is 643728649. The reversal of 643728611 is 116827346.

643728611 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an a-pointer prime, because the next prime (643728649) can be obtained adding 643728611 to its sum of digits (38).

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-643728611 is a prime.

It is not a weakly prime, because it can be changed into another prime (643728601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321864305 + 321864306.

It is an arithmetic number, because the mean of its divisors is an integer number (321864306).

Almost surely, 2^643728611 is an apocalyptic number.

643728611 is a deficient number, since it is larger than the sum of its proper divisors (1).

643728611 is an equidigital number, since it uses as much as digits as its factorization.

643728611 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 38.

The square root of 643728611 is about 25371.8074050707. The cubic root of 643728611 is about 863.4441883296. Note that the first 3 decimals are identical.

The spelling of 643728611 in words is "six hundred forty-three million, seven hundred twenty-eight thousand, six hundred eleven".