638657218919 has 2 divisors, whose sum is σ = 638657218920. Its totient is φ = 638657218918.

The previous prime is 638657218867. The next prime is 638657218937. The reversal of 638657218919 is 919812756836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638657218919 - 2²⁰ = 638656170343 is a prime.

It is a super-2 number, since 2×638657218919² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (638657218939) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319328609459 + 319328609460.

It is an arithmetic number, because the mean of its divisors is an integer number (319328609460).

Almost surely, 2^638657218919 is an apocalyptic number.

638657218919 is a deficient number, since it is larger than the sum of its proper divisors (1).

638657218919 is an equidigital number, since it uses as much as digits as its factorization.

638657218919 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 39191040, while the sum is 65.

The spelling of 638657218919 in words is "six hundred thirty-eight billion, six hundred fifty-seven million, two hundred eighteen thousand, nine hundred nineteen".