638544217 has 2 divisors, whose sum is σ = 638544218. Its totient is φ = 638544216.

The previous prime is 638544139. The next prime is 638544227. The reversal of 638544217 is 712445836.

638544217 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 can be written as a sum of positive squares in only one way, i.e., 633830976 + 4713241 = 25176^2 + 2171^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638544217 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 638544217.

It is not a weakly prime, because it can be changed into another prime (638544227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319272108 + 319272109.

It is an arithmetic number, because the mean of its divisors is an integer number (319272109).

Almost surely, 2^638544217 is an apocalyptic number.

It is an amenable number.

638544217 is a deficient number, since it is larger than the sum of its proper divisors (1).

638544217 is an equidigital number, since it uses as much as digits as its factorization.

638544217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 161280, while the sum is 40.

The square root of 638544217 is about 25269.4324629581. The cubic root of 638544217 is about 861.1199654960.

The spelling of 638544217 in words is "six hundred thirty-eight million, five hundred forty-four thousand, two hundred seventeen".