638819 has 2 divisors, whose sum is σ = 638820. Its totient is φ = 638818.

The previous prime is 638801. The next prime is 638839. The reversal of 638819 is 918836.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-638819 is a prime.

It is a super-2 number, since 2×638819² = 816179429522, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (638839) 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, 319409 + 319410.

It is an arithmetic number, because the mean of its divisors is an integer number (319410).

2⁶³⁸⁸¹⁹ is an apocalyptic number.

638819 is a deficient number, since it is larger than the sum of its proper divisors (1).

638819 is an equidigital number, since it uses as much as digits as its factorization.

638819 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 35.

The square root of 638819 is about 799.2615341676. The cubic root of 638819 is about 86.1243468921.

The spelling of 638819 in words is "six hundred thirty-eight thousand, eight hundred nineteen".