643938013 has 2 divisors, whose sum is σ = 643938014. Its totient is φ = 643938012.

The previous prime is 643937999. The next prime is 643938049. The reversal of 643938013 is 310839346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 642014244 + 1923769 = 25338^2 + 1387^2 .

It is a cyclic number.

It is not a de Polignac number, because 643938013 - 2⁹ = 643937501 is a prime.

It is equal to p_33494590 and since 643938013 and 33494590 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643938073) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321969006 + 321969007.

It is an arithmetic number, because the mean of its divisors is an integer number (321969007).

Almost surely, 2^643938013 is an apocalyptic number.

It is an amenable number.

643938013 is a deficient number, since it is larger than the sum of its proper divisors (1).

643938013 is an equidigital number, since it uses as much as digits as its factorization.

643938013 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 46656, while the sum is 37.

The square root of 643938013 is about 25375.9337365150. The cubic root of 643938013 is about 863.5378030068.

The spelling of 643938013 in words is "six hundred forty-three million, nine hundred thirty-eight thousand, thirteen".