20513521022121 has 6 divisors (see below), whose sum is σ = 29630641476410. Its totient is φ = 13675680681408.

The previous prime is 20513521022117. The next prime is 20513521022123. The reversal of 20513521022121 is 12122012531502.

20513521022121 is a `hidden beast` number, since 2 + 0 + 5 + 13 + 521 + 0 + 2 + 2 + 121 = 666.

It can be written as a sum of positive squares in only one way, i.e., 10348831641600 + 10164689380521 = 3216960^2 + 3188211^2 .

It is not a de Polignac number, because 20513521022121 - 2² = 20513521022117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20513521022123) 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, 1139640056776 + ... + 1139640056793.

Almost surely, 2^{20513521022121} is an apocalyptic number.

It is an amenable number.

20513521022121 is a deficient number, since it is larger than the sum of its proper divisors (9117120454289).

20513521022121 is a wasteful number, since it uses less digits than its factorization.

20513521022121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2279280113575 (or 2279280113572 counting only the distinct ones).

The product of its (nonzero) digits is 2400, while the sum is 27.

Adding to 20513521022121 its reverse (12122012531502), we get a palindrome (32635533553623).

The spelling of 20513521022121 in words is "twenty trillion, five hundred thirteen billion, five hundred twenty-one million, twenty-two thousand, one hundred twenty-one".