21201101212221 has 64 divisors (see below), whose sum is σ = 37474740080640. Its totient is φ = 11582611381440.

The previous prime is 21201101212211. The next prime is 21201101212261. The reversal of 21201101212221 is 12221210110212.

21201101212221 is a `hidden beast` number, since 2 + 120 + 110 + 1 + 212 + 221 = 666.

It is not a de Polignac number, because 21201101212221 - 2⁹ = 21201101211709 is a prime.

It is a super-2 number, since 2×21201101212221² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21201101212194 and 21201101212203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201101212211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 7884091 + ... + 10225511.

It is an arithmetic number, because the mean of its divisors is an integer number (585542813760).

Almost surely, 2^{21201101212221} is an apocalyptic number.

21201101212221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21201101212221 is a deficient number, since it is larger than the sum of its proper divisors (16273638868419).

21201101212221 is a wasteful number, since it uses less digits than its factorization.

21201101212221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2343543 (or 2343537 counting only the distinct ones).

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

Adding to 21201101212221 its reverse (12221210110212), we get a palindrome (33422311322433).

The spelling of 21201101212221 in words is "twenty-one trillion, two hundred one billion, one hundred one million, two hundred twelve thousand, two hundred twenty-one".