643863511 has 2 divisors, whose sum is σ = 643863512. Its totient is φ = 643863510.

The previous prime is 643863463. The next prime is 643863533. The reversal of 643863511 is 115368346.

643863511 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 643863511 - 2¹⁹ = 643339223 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (643863911) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321931755 + 321931756.

It is an arithmetic number, because the mean of its divisors is an integer number (321931756).

Almost surely, 2^643863511 is an apocalyptic number.

643863511 is a deficient number, since it is larger than the sum of its proper divisors (1).

643863511 is an equidigital number, since it uses as much as digits as its factorization.

643863511 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 51840, while the sum is 37.

The square root of 643863511 is about 25374.4657283656. The cubic root of 643863511 is about 863.5044986755.

The spelling of 643863511 in words is "six hundred forty-three million, eight hundred sixty-three thousand, five hundred eleven".