643765387 has 2 divisors, whose sum is σ = 643765388. Its totient is φ = 643765386.

The previous prime is 643765379. The next prime is 643765433. The reversal of 643765387 is 783567346.

It is a happy number.

643765387 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 643765387 - 2³ = 643765379 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 643765387.

It is not a weakly prime, because it can be changed into another prime (643765337) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 321882693 + 321882694.

It is an arithmetic number, because the mean of its divisors is an integer number (321882694).

Almost surely, 2^643765387 is an apocalyptic number.

643765387 is a deficient number, since it is larger than the sum of its proper divisors (1).

643765387 is an equidigital number, since it uses as much as digits as its factorization.

643765387 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2540160, while the sum is 49.

The square root of 643765387 is about 25372.5321361507. The cubic root of 643765387 is about 863.4606307756.

It can be divided in two parts, 6437 and 65387, that added together give a square (71824 = 268²).

The spelling of 643765387 in words is "six hundred forty-three million, seven hundred sixty-five thousand, three hundred eighty-seven".