643504447 has 2 divisors, whose sum is σ = 643504448. Its totient is φ = 643504446.

The previous prime is 643504423. The next prime is 643504501. The reversal of 643504447 is 744405346.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643504447 - 2⁷ = 643504319 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643594447) 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, 321752223 + 321752224.

It is an arithmetic number, because the mean of its divisors is an integer number (321752224).

Almost surely, 2^643504447 is an apocalyptic number.

643504447 is a deficient number, since it is larger than the sum of its proper divisors (1).

643504447 is an equidigital number, since it uses as much as digits as its factorization.

643504447 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 161280, while the sum is 37.

The square root of 643504447 is about 25367.3894399877. The cubic root of 643504447 is about 863.3439516922.

The spelling of 643504447 in words is "six hundred forty-three million, five hundred four thousand, four hundred forty-seven".