21012202221021 has 24 divisors (see below), whose sum is σ = 33111198304704. Its totient is φ = 12734259754560.

The previous prime is 21012202220983. The next prime is 21012202221077. The reversal of 21012202221021 is 12012220221012.

It is a happy number.

21012202221021 is a `hidden beast` number, since 210 + 1 + 220 + 2 + 2 + 210 + 21 = 666.

It is not a de Polignac number, because 21012202221021 - 2⁶ = 21012202220957 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21012202220985 and 21012202221003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21012202220021) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 284121 + ... + 6488846.

It is an arithmetic number, because the mean of its divisors is an integer number (1379633262696).

Almost surely, 2^{21012202221021} is an apocalyptic number.

It is an amenable number.

21012202221021 is a deficient number, since it is larger than the sum of its proper divisors (12098996083683).

21012202221021 is a wasteful number, since it uses less digits than its factorization.

21012202221021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6804321 (or 6804318 counting only the distinct ones).

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

Adding to 21012202221021 its reverse (12012220221012), we get a palindrome (33024422442033).

Subtracting from 21012202221021 its reverse (12012220221012), we obtain a square (8999982000009 = 2999997²).

It can be divided in two parts, 2101220 and 2221021, that added together give a square (4322241 = 2079²).

The spelling of 21012202221021 in words is "twenty-one trillion, twelve billion, two hundred two million, two hundred twenty-one thousand, twenty-one".