643784699 has 2 divisors, whose sum is σ = 643784700. Its totient is φ = 643784698.

The previous prime is 643784689. The next prime is 643784707. The reversal of 643784699 is 996487346.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643784699 - 2⁴ = 643784683 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (643784639) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321892349 + 321892350.

It is an arithmetic number, because the mean of its divisors is an integer number (321892350).

Almost surely, 2^643784699 is an apocalyptic number.

643784699 is a deficient number, since it is larger than the sum of its proper divisors (1).

643784699 is an equidigital number, since it uses as much as digits as its factorization.

643784699 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7838208, while the sum is 56.

The square root of 643784699 is about 25372.9127023288. The cubic root of 643784699 is about 863.4692648657.

The spelling of 643784699 in words is "six hundred forty-three million, seven hundred eighty-four thousand, six hundred ninety-nine".