643544123 has 2 divisors, whose sum is σ = 643544124. Its totient is φ = 643544122.

The previous prime is 643544113. The next prime is 643544141. The reversal of 643544123 is 321445346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643544123 - 2⁴ = 643544107 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643544123.

It is not a weakly prime, because it can be changed into another prime (643544113) 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, 321772061 + 321772062.

It is an arithmetic number, because the mean of its divisors is an integer number (321772062).

Almost surely, 2^643544123 is an apocalyptic number.

643544123 is a deficient number, since it is larger than the sum of its proper divisors (1).

643544123 is an equidigital number, since it uses as much as digits as its factorization.

643544123 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 643544123 is about 25368.1714555858. The cubic root of 643544123 is about 863.3616948126.

Adding to 643544123 its reverse (321445346), we get a palindrome (964989469).

The spelling of 643544123 in words is "six hundred forty-three million, five hundred forty-four thousand, one hundred twenty-three".