638440237 has 2 divisors, whose sum is σ = 638440238. Its totient is φ = 638440236.

The previous prime is 638440207. The next prime is 638440241. The reversal of 638440237 is 732044836.

It is a happy number.

638440237 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., 343768681 + 294671556 = 18541^2 + 17166^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638440237 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 638440196 and 638440205.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638440207) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319220118 + 319220119.

It is an arithmetic number, because the mean of its divisors is an integer number (319220119).

Almost surely, 2^638440237 is an apocalyptic number.

It is an amenable number.

638440237 is a deficient number, since it is larger than the sum of its proper divisors (1).

638440237 is an equidigital number, since it uses as much as digits as its factorization.

638440237 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96768, while the sum is 37.

The square root of 638440237 is about 25267.3749526934. The cubic root of 638440237 is about 861.0732216098.

The spelling of 638440237 in words is "six hundred thirty-eight million, four hundred forty thousand, two hundred thirty-seven".