21020020221 has 8 divisors (see below), whose sum is σ = 28028116480. Its totient is φ = 14012635392.

The previous prime is 21020020201. The next prime is 21020020237. The reversal of 21020020221 is 12202002012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a de Polignac number, because none of the positive numbers 2^k-21020020221 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21020020197 and 21020020206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21020020201) 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 7 ways as a sum of consecutive naturals, for example, 104605 + ... + 230178.

It is an arithmetic number, because the mean of its divisors is an integer number (3503514560).

Almost surely, 2^21020020221 is an apocalyptic number.

It is an amenable number.

21020020221 is a deficient number, since it is larger than the sum of its proper divisors (7008096259).

21020020221 is a wasteful number, since it uses less digits than its factorization.

21020020221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355715.

The product of its (nonzero) digits is 32, while the sum is 12.

Adding to 21020020221 its reverse (12202002012), we get a palindrome (33222022233).

The spelling of 21020020221 in words is "twenty-one billion, twenty million, twenty thousand, two hundred twenty-one".