21202021211121 has 6 divisors (see below), whose sum is σ = 30625141749410. Its totient is φ = 14134680807408.

The previous prime is 21202021211051. The next prime is 21202021211159. The reversal of 21202021211121 is 12111212020212.

It can be written as a sum of positive squares in only one way, i.e., 18005077211121 + 3196944000000 = 4243239^2 + 1788000^2 .

It is not a de Polignac number, because 21202021211121 - 2¹⁴ = 21202021194737 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21202021211094 and 21202021211103.

It is not an unprimeable number, because it can be changed into a prime (21202020211121) 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, 1177890067276 + ... + 1177890067293.

Almost surely, 2^{21202021211121} is an apocalyptic number.

It is an amenable number.

21202021211121 is a deficient number, since it is larger than the sum of its proper divisors (9423120538289).

21202021211121 is a wasteful number, since it uses less digits than its factorization.

21202021211121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2355780134575 (or 2355780134572 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21202021211121 its reverse (12111212020212), we get a palindrome (33313233231333).

The spelling of 21202021211121 in words is "twenty-one trillion, two hundred two billion, twenty-one million, two hundred eleven thousand, one hundred twenty-one".