643523189 has 2 divisors, whose sum is σ = 643523190. Its totient is φ = 643523188.

The previous prime is 643523171. The next prime is 643523227. The reversal of 643523189 is 981325346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 568440964 + 75082225 = 23842^2 + 8665^2 .

It is a cyclic number.

It is not a de Polignac number, because 643523189 - 2¹⁶ = 643457653 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643523119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321761594 + 321761595.

It is an arithmetic number, because the mean of its divisors is an integer number (321761595).

Almost surely, 2^643523189 is an apocalyptic number.

It is an amenable number.

643523189 is a deficient number, since it is larger than the sum of its proper divisors (1).

643523189 is an equidigital number, since it uses as much as digits as its factorization.

643523189 is an evil number, because the sum of its binary digits is even.

The product of its digits is 155520, while the sum is 41.

The square root of 643523189 is about 25367.7588485857. The cubic root of 643523189 is about 863.3523332117.

It can be divided in two parts, 64 and 3523189, that added together give a palindrome (3523253).

The spelling of 643523189 in words is "six hundred forty-three million, five hundred twenty-three thousand, one hundred eighty-nine".