643784663 has 2 divisors, whose sum is σ = 643784664. Its totient is φ = 643784662.

The previous prime is 643784639. The next prime is 643784671. The reversal of 643784663 is 366487346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643784663 - 2⁶ = 643784599 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643784633) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321892331 + 321892332.

It is an arithmetic number, because the mean of its divisors is an integer number (321892332).

Almost surely, 2^643784663 is an apocalyptic number.

643784663 is a deficient number, since it is larger than the sum of its proper divisors (1).

643784663 is an equidigital number, since it uses as much as digits as its factorization.

643784663 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1741824, while the sum is 47.

The square root of 643784663 is about 25372.9119929109. The cubic root of 643784663 is about 863.4692487708.

The spelling of 643784663 in words is "six hundred forty-three million, seven hundred eighty-four thousand, six hundred sixty-three".