643542629 has 2 divisors, whose sum is σ = 643542630. Its totient is φ = 643542628.

The previous prime is 643542623. The next prime is 643542637. The reversal of 643542629 is 926245346.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 630110404 + 13432225 = 25102^2 + 3665^2 .

It is a cyclic number.

It is not a de Polignac number, because 643542629 - 2²⁰ = 642494053 is a prime.

It is a Sophie Germain 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 (643542623) 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, 321771314 + 321771315.

It is an arithmetic number, because the mean of its divisors is an integer number (321771315).

Almost surely, 2^643542629 is an apocalyptic number.

It is an amenable number.

643542629 is a deficient number, since it is larger than the sum of its proper divisors (1).

643542629 is an equidigital number, since it uses as much as digits as its factorization.

643542629 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 311040, while the sum is 41.

The square root of 643542629 is about 25368.1420092209. The cubic root of 643542629 is about 863.3610267085.

The spelling of 643542629 in words is "six hundred forty-three million, five hundred forty-two thousand, six hundred twenty-nine".