21201222021020 has 96 divisors (see below), whose sum is σ = 46993942195200. Its totient is φ = 8012220378624.

The previous prime is 21201222021011. The next prime is 21201222021029. The reversal of 21201222021020 is 2012022210212.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (21201222021011) and next prime (21201222021029).

It is a self number, because there is not a number n which added to its sum of digits gives 21201222021020.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21201222021029) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 205209536 + ... + 205312824.

It is an arithmetic number, because the mean of its divisors is an integer number (489520231200).

Almost surely, 2^{21201222021020} is an apocalyptic number.

21201222021020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21201222021020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23496971097600).

21201222021020 is an abundant number, since it is smaller than the sum of its proper divisors (25792720174180).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21201222021020 is a wasteful number, since it uses less digits than its factorization.

21201222021020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 104787 (or 104785 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 17.

Adding to 21201222021020 its reverse (2012022210212), we get a palindrome (23213244231232).

The spelling of 21201222021020 in words is "twenty-one trillion, two hundred one billion, two hundred twenty-two million, twenty-one thousand, twenty".