638646419 has 2 divisors, whose sum is σ = 638646420. Its totient is φ = 638646418.

The previous prime is 638646409. The next prime is 638646499. The reversal of 638646419 is 914646836.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 638646419 - 2²⁰ = 637597843 is a prime.

It is a super-2 number, since 2×638646419² = 815738497003047122, which contains 22 as substring.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (638646409) 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, 319323209 + 319323210.

It is an arithmetic number, because the mean of its divisors is an integer number (319323210).

Almost surely, 2^638646419 is an apocalyptic number.

638646419 is a deficient number, since it is larger than the sum of its proper divisors (1).

638646419 is an equidigital number, since it uses as much as digits as its factorization.

638646419 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 746496, while the sum is 47.

The square root of 638646419 is about 25271.4546277020. The cubic root of 638646419 is about 861.1659051430.

The spelling of 638646419 in words is "six hundred thirty-eight million, six hundred forty-six thousand, four hundred nineteen".