643622009 has 2 divisors, whose sum is σ = 643622010. Its totient is φ = 643622008.

The previous prime is 643621943. The next prime is 643622011. The reversal of 643622009 is 900226346.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 589275625 + 54346384 = 24275^2 + 7372^2 .

It is a cyclic number.

It is not a de Polignac number, because 643622009 - 2²⁰ = 642573433 is a prime.

Together with 643622011, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (643622069) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321811004 + 321811005.

It is an arithmetic number, because the mean of its divisors is an integer number (321811005).

Almost surely, 2^643622009 is an apocalyptic number.

It is an amenable number.

643622009 is a deficient number, since it is larger than the sum of its proper divisors (1).

643622009 is an equidigital number, since it uses as much as digits as its factorization.

643622009 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 15552, while the sum is 32.

The square root of 643622009 is about 25369.7065217554. The cubic root of 643622009 is about 863.3965233369.

The spelling of 643622009 in words is "six hundred forty-three million, six hundred twenty-two thousand, nine".