638042723 has 2 divisors, whose sum is σ = 638042724. Its totient is φ = 638042722.

The previous prime is 638042681. The next prime is 638042731. The reversal of 638042723 is 327240836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638042723 - 2¹⁰ = 638041699 is a prime.

It is not a weakly prime, because it can be changed into another prime (638044723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319021361 + 319021362.

It is an arithmetic number, because the mean of its divisors is an integer number (319021362).

Almost surely, 2^638042723 is an apocalyptic number.

638042723 is a deficient number, since it is larger than the sum of its proper divisors (1).

638042723 is an equidigital number, since it uses as much as digits as its factorization.

638042723 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 48384, while the sum is 35.

The square root of 638042723 is about 25259.5075763563. The cubic root of 638042723 is about 860.8944736209.

The spelling of 638042723 in words is "six hundred thirty-eight million, forty-two thousand, seven hundred twenty-three".