638081789 has 2 divisors, whose sum is σ = 638081790. Its totient is φ = 638081788.

The previous prime is 638081771. The next prime is 638081813. The reversal of 638081789 is 987180836.

It is a happy number.

638081789 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 can be written as a sum of positive squares in only one way, i.e., 634536100 + 3545689 = 25190^2 + 1883^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638081789 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638081089) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319040894 + 319040895.

It is an arithmetic number, because the mean of its divisors is an integer number (319040895).

Almost surely, 2^638081789 is an apocalyptic number.

It is an amenable number.

638081789 is a deficient number, since it is larger than the sum of its proper divisors (1).

638081789 is an equidigital number, since it uses as much as digits as its factorization.

638081789 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 580608, while the sum is 50.

The square root of 638081789 is about 25260.2808575043. The cubic root of 638081789 is about 860.9120435087.

The spelling of 638081789 in words is "six hundred thirty-eight million, eighty-one thousand, seven hundred eighty-nine".