159663681 has 6 divisors (see below), whose sum is σ = 230625330. Its totient is φ = 106442448.

The previous prime is 159663667. The next prime is 159663683. The reversal of 159663681 is 186366951.

159663681 is a `hidden beast` number, since 1 + 5 + 9 + 6 + 636 + 8 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 138650625 + 21013056 = 11775^2 + 4584^2 .

It is a de Polignac number, because none of the positive numbers 2^k-159663681 is a prime.

It is a super-2 number, since 2×159663681² = 50984982060939522, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (159663683) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 8870196 + ... + 8870213.

It is an arithmetic number, because the mean of its divisors is an integer number (38437555).

Almost surely, 2^159663681 is an apocalyptic number.

It is an amenable number.

159663681 is a deficient number, since it is larger than the sum of its proper divisors (70961649).

159663681 is a wasteful number, since it uses less digits than its factorization.

159663681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17740415 (or 17740412 counting only the distinct ones).

The product of its digits is 233280, while the sum is 45.

The square root of 159663681 is about 12635.8094714981. The cubic root of 159663681 is about 542.5028772314.

The spelling of 159663681 in words is "one hundred fifty-nine million, six hundred sixty-three thousand, six hundred eighty-one".