643316917 has 2 divisors, whose sum is σ = 643316918. Its totient is φ = 643316916.

The previous prime is 643316911. The next prime is 643316951. The reversal of 643316917 is 719613346.

643316917 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 584962596 + 58354321 = 24186^2 + 7639^2 .

It is a cyclic number.

It is not a de Polignac number, because 643316917 - 2³ = 643316909 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643316917.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643316911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321658458 + 321658459.

It is an arithmetic number, because the mean of its divisors is an integer number (321658459).

Almost surely, 2^643316917 is an apocalyptic number.

It is an amenable number.

643316917 is a deficient number, since it is larger than the sum of its proper divisors (1).

643316917 is an equidigital number, since it uses as much as digits as its factorization.

643316917 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 81648, while the sum is 40.

The square root of 643316917 is about 25363.6928896405. The cubic root of 643316917 is about 863.2600783422.

The spelling of 643316917 in words is "six hundred forty-three million, three hundred sixteen thousand, nine hundred seventeen".