638780780005 has 4 divisors (see below), whose sum is σ = 766536936012. Its totient is φ = 511024624000.

The previous prime is 638780779981. The next prime is 638780780063. The reversal of 638780780005 is 500087087836.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 374484026401 + 264296753604 = 611951^2 + 514098^2 .

It is not a de Polignac number, because 638780780005 - 2⁹ = 638780779493 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 63878077996 + ... + 63878078005.

It is an arithmetic number, because the mean of its divisors is an integer number (191634234003).

Almost surely, 2^638780780005 is an apocalyptic number.

It is an amenable number.

638780780005 is a deficient number, since it is larger than the sum of its proper divisors (127756156007).

638780780005 is a wasteful number, since it uses less digits than its factorization.

638780780005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 127756156006.

The product of its (nonzero) digits is 2257920, while the sum is 52.

The spelling of 638780780005 in words is "six hundred thirty-eight billion, seven hundred eighty million, seven hundred eighty thousand, five".