643784887 has 2 divisors, whose sum is σ = 643784888. Its totient is φ = 643784886.

The previous prime is 643784879. The next prime is 643784909. The reversal of 643784887 is 788487346.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643784887 - 2³ = 643784879 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643784837) 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, 321892443 + 321892444.

It is an arithmetic number, because the mean of its divisors is an integer number (321892444).

Almost surely, 2^643784887 is an apocalyptic number.

643784887 is a deficient number, since it is larger than the sum of its proper divisors (1).

643784887 is an equidigital number, since it uses as much as digits as its factorization.

643784887 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7225344, while the sum is 55.

The square root of 643784887 is about 25372.9164070668. The cubic root of 643784887 is about 863.4693489167.

The spelling of 643784887 in words is "six hundred forty-three million, seven hundred eighty-four thousand, eight hundred eighty-seven".