3638666885841 has 81 divisors (see below), whose sum is σ = 5796336938769. Its totient is φ = 2198572144704.

The previous prime is 3638666885803. The next prime is 3638666885849. The reversal of 3638666885841 is 1485886668363.

The square root of 3638666885841 is 1907529.

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

It can be written as a sum of positive squares in 4 ways, for example, as 348448187025 + 3290218698816 = 590295^2 + 1813896^2 .

It is not a de Polignac number, because 3638666885841 - 2⁷ = 3638666885713 is a prime.

It is a super-2 number, since 2×3638666885841² (a number of 26 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 3638666885841.

It is not an unprimeable number, because it can be changed into a prime (3638666885849) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 4389223815 + ... + 4389224643.

Almost surely, 2^{3638666885841} is an apocalyptic number.

3638666885841 is the 1907529-th square number.

3638666885841 is the 953765-th centered octagonal number.

It is an amenable number.

3638666885841 is a deficient number, since it is larger than the sum of its proper divisors (2157670052928).

3638666885841 is an frugal number, since it uses more digits than its factorization.

3638666885841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1808 (or 904 counting only the distinct ones).

The product of its digits is 955514880, while the sum is 72.

The spelling of 3638666885841 in words is "three trillion, six hundred thirty-eight billion, six hundred sixty-six million, eight hundred eighty-five thousand, eight hundred forty-one".