21201101111221 has 32 divisors (see below), whose sum is σ = 21578569320672. Its totient is φ = 20827605565440.

The previous prime is 21201101111213. The next prime is 21201101111227. The reversal of 21201101111221 is 12211110110212.

It can be written as a sum of positive squares in 16 ways, for example, as 5185817463121 + 16015283648100 = 2277239^2 + 4001910^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201101111221 - 2³ = 21201101111213 is a prime.

It is a super-2 number, since 2×21201101111221² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21201101111195 and 21201101111204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201101111227) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 12177541411 + ... + 12177543151.

It is an arithmetic number, because the mean of its divisors is an integer number (674330291271).

Almost surely, 2^{21201101111221} is an apocalyptic number.

It is an amenable number.

21201101111221 is a deficient number, since it is larger than the sum of its proper divisors (377468209451).

21201101111221 is a wasteful number, since it uses less digits than its factorization.

21201101111221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3529.

The product of its (nonzero) digits is 16, while the sum is 16.

Adding to 21201101111221 its reverse (12211110110212), we get a palindrome (33412211221433).

The spelling of 21201101111221 in words is "twenty-one trillion, two hundred one billion, one hundred one million, one hundred eleven thousand, two hundred twenty-one".