638865419 has 2 divisors, whose sum is σ = 638865420. Its totient is φ = 638865418.

The previous prime is 638865397. The next prime is 638865433. The reversal of 638865419 is 914568836.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 638865419 - 2⁸ = 638865163 is a prime.

It is a super-2 number, since 2×638865419² = 816298047188091122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (638865449) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 319432709 + 319432710.

It is an arithmetic number, because the mean of its divisors is an integer number (319432710).

Almost surely, 2^638865419 is an apocalyptic number.

638865419 is a deficient number, since it is larger than the sum of its proper divisors (1).

638865419 is an equidigital number, since it uses as much as digits as its factorization.

638865419 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1244160, while the sum is 50.

The square root of 638865419 is about 25275.7872083146. The cubic root of 638865419 is about 861.2643288166.

The spelling of 638865419 in words is "six hundred thirty-eight million, eight hundred sixty-five thousand, four hundred nineteen".