638613782656 has 16 divisors (see below), whose sum is σ = 1272238395390. Its totient is φ = 319306891264.

The previous prime is 638613782647. The next prime is 638613782669. The reversal of 638613782656 is 656287316836.

It can be written as a sum of positive squares in only one way, i.e., 613464897600 + 25148885056 = 783240^2 + 158584^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a junction number, because it is equal to n+sod(n) for n = 638613782594 and 638613782603.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2494584961 + ... + 2494585216.

Almost surely, 2^638613782656 is an apocalyptic number.

It is an amenable number.

638613782656 is a deficient number, since it is larger than the sum of its proper divisors (633624612734).

638613782656 is an equidigital number, since it uses as much as digits as its factorization.

638613782656 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4989170191 (or 4989170179 counting only the distinct ones).

The product of its digits is 52254720, while the sum is 61.

The spelling of 638613782656 in words is "six hundred thirty-eight billion, six hundred thirteen million, seven hundred eighty-two thousand, six hundred fifty-six".