638717 has 2 divisors, whose sum is σ = 638718. Its totient is φ = 638716.

The previous prime is 638699. The next prime is 638719. The reversal of 638717 is 717836.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 630436 + 8281 = 794^2 + 91^2 .

It is a cyclic number.

It is not a de Polignac number, because 638717 - 2¹⁴ = 622333 is a prime.

Together with 638719, it forms a pair of twin primes.

It is a Chen prime.

It is an Ulam number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638719) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319358 + 319359.

It is an arithmetic number, because the mean of its divisors is an integer number (319359).

2⁶³⁸⁷¹⁷ is an apocalyptic number.

It is an amenable number.

638717 is a deficient number, since it is larger than the sum of its proper divisors (1).

638717 is an equidigital number, since it uses as much as digits as its factorization.

638717 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7056, while the sum is 32.

The square root of 638717 is about 799.1977227195. The cubic root of 638717 is about 86.1197628337.

It can be divided in two parts, 638 and 717, that multiplied together give a triangular number (457446 = T₉₅₆).

The spelling of 638717 in words is "six hundred thirty-eight thousand, seven hundred seventeen".