638613782666 has 8 divisors (see below), whose sum is σ = 960196021284. Its totient is φ = 318548442240.

The previous prime is 638613782647. The next prime is 638613782669. The reversal of 638613782666 is 666287316836.

It can be written as a sum of positive squares in 2 ways, for example, as 581972162641 + 56641620025 = 762871^2 + 237995^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a junction number, because it is equal to n+sod(n) for n = 638613782599 and 638613782608.

It is not an unprimeable number, because it can be changed into a prime (638613782669) 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 in 3 ways as a sum of consecutive naturals, for example, 379223495 + ... + 379225178.

Almost surely, 2^638613782666 is an apocalyptic number.

638613782666 is a deficient number, since it is larger than the sum of its proper divisors (321582238618).

638613782666 is a wasteful number, since it uses less digits than its factorization.

638613782666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 758449096.

The product of its digits is 62705664, while the sum is 62.

The spelling of 638613782666 in words is "six hundred thirty-eight billion, six hundred thirteen million, seven hundred eighty-two thousand, six hundred sixty-six".