643421543 has 2 divisors, whose sum is σ = 643421544. Its totient is φ = 643421542.

The previous prime is 643421539. The next prime is 643421563. The reversal of 643421543 is 345124346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643421543 - 2² = 643421539 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643421563) 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, 321710771 + 321710772.

It is an arithmetic number, because the mean of its divisors is an integer number (321710772).

Almost surely, 2^643421543 is an apocalyptic number.

643421543 is a deficient number, since it is larger than the sum of its proper divisors (1).

643421543 is an equidigital number, since it uses as much as digits as its factorization.

643421543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 34560, while the sum is 32.

The square root of 643421543 is about 25365.7553209046. The cubic root of 643421543 is about 863.3068746415.

Adding to 643421543 its reverse (345124346), we get a palindrome (988545889).

The spelling of 643421543 in words is "six hundred forty-three million, four hundred twenty-one thousand, five hundred forty-three".