21201122002221 has 72 divisors (see below), whose sum is σ = 36953508402720. Its totient is φ = 12111496723872.

The previous prime is 21201122002213. The next prime is 21201122002241. The reversal of 21201122002221 is 12220022110212.

It is a happy number.

21201122002221 is a `hidden beast` number, since 21 + 201 + 1 + 220 + 0 + 2 + 221 = 666.

It is not a de Polignac number, because 21201122002221 - 2³ = 21201122002213 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21201122002194 and 21201122002203.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201122002211) by changing a digit.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 42102910 + ... + 42603488.

It is an arithmetic number, because the mean of its divisors is an integer number (513243172260).

Almost surely, 2^{21201122002221} is an apocalyptic number.

21201122002221 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

21201122002221 is a deficient number, since it is larger than the sum of its proper divisors (15752386400499).

21201122002221 is an equidigital number, since it uses as much as digits as its factorization.

21201122002221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 504165 (or 504146 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

Adding to 21201122002221 its reverse (12220022110212), we get a palindrome (33421144112433).

The spelling of 21201122002221 in words is "twenty-one trillion, two hundred one billion, one hundred twenty-two million, two thousand, two hundred twenty-one".