638719 has 2 divisors, whose sum is σ = 638720.
Its totient is φ = 638718.
The previous prime is 638717. The next prime is 638767. The reversal of 638719 is 917836.
It is a weak prime.
It is a cyclic number.
It is not a de Polignac number, because 638719 - 21 = 638717 is a prime.
It is a super-2 number, since 2×6387192 = 815923921922, which contains 22 as substring.
Together with 638717, it forms a pair of twin primes.
It is a plaindrome in base 14 and base 16.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (638717) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319359 + 319360.
It is an arithmetic number, because the mean of its divisors is an integer number (319360).
2638719 is an apocalyptic number.
638719 is a deficient number, since it is larger than the sum of its proper divisors (1).
638719 is an equidigital number, since it uses as much as digits as its factorization.
638719 is an evil number, because the sum of its binary digits is even.
The product of its digits is 9072, while the sum is 34.
The square root of 638719 is about 799.1989739733.
The cubic root of 638719 is about 86.1198527218.
The spelling of 638719 in words is "six hundred thirty-eight thousand, seven hundred nineteen".