638067061681 has 9 divisors (see below), whose sum is σ = 742247780331. Its totient is φ = 546909831552.

The previous prime is 638067061661. The next prime is 638067061799. The reversal of 638067061681 is 186160760836.

The square root of 638067061681 is 798791.

It is a perfect power (a square), and thus also a powerful number.

638067061681 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 28755680625 + 609311381056 = 169575^2 + 780584^2 .

It is not a de Polignac number, because 638067061681 - 2⁵ = 638067061649 is a prime.

It is a super-2 number, since 2×638067061681² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638067061661) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 5534481 + ... + 5648593.

Almost surely, 2^638067061681 is an apocalyptic number.

638067061681 is the 798791-st square number.

638067061681 is the 399396-th centered octagonal number.

It is an amenable number.

638067061681 is a deficient number, since it is larger than the sum of its proper divisors (104180718650).

638067061681 is an frugal number, since it uses more digits than its factorization.

638067061681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 228240 (or 114120 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 52.

The spelling of 638067061681 in words is "six hundred thirty-eight billion, sixty-seven million, sixty-one thousand, six hundred eighty-one".