163506543220521 has 6 divisors (see below), whose sum is σ = 236176117985210. Its totient is φ = 109004362147008.

The previous prime is 163506543220469. The next prime is 163506543220547. The reversal of 163506543220521 is 125022345605361.

163506543220521 is a `hidden beast` number, since 1 + 6 + 3 + 5 + 0 + 6 + 5 + 432 + 205 + 2 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 143373419090496 + 20133124130025 = 11973864^2 + 4486995^2 .

It is not a de Polignac number, because 163506543220521 - 2¹⁸ = 163506542958377 is a prime.

It is a super-2 number, since 2×163506543220521² (a number of 29 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (163506543220571) 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, 9083696845576 + ... + 9083696845593.

Almost surely, 2^{163506543220521} is an apocalyptic number.

It is an amenable number.

163506543220521 is a deficient number, since it is larger than the sum of its proper divisors (72669574764689).

163506543220521 is a wasteful number, since it uses less digits than its factorization.

163506543220521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18167393691175 (or 18167393691172 counting only the distinct ones).

The product of its (nonzero) digits is 1296000, while the sum is 45.

Adding to 163506543220521 its reverse (125022345605361), we get a palindrome (288528888825882).

The spelling of 163506543220521 in words is "one hundred sixty-three trillion, five hundred six billion, five hundred forty-three million, two hundred twenty thousand, five hundred twenty-one".