21220100221021 has 4 divisors (see below), whose sum is σ = 22852415622652. Its totient is φ = 19587784819392.

The previous prime is 21220100221013. The next prime is 21220100221031. The reversal of 21220100221021 is 12012200102212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 7364873268900 + 13855226952121 = 2713830^2 + 3722261^2 .

It is a cyclic number.

It is not a de Polignac number, because 21220100221021 - 2³ = 21220100221013 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21220100220986 and 21220100221004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220100221031) 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 3 ways as a sum of consecutive naturals, for example, 816157700796 + ... + 816157700821.

It is an arithmetic number, because the mean of its divisors is an integer number (5713103905663).

Almost surely, 2^{21220100221021} is an apocalyptic number.

It is an amenable number.

21220100221021 is a deficient number, since it is larger than the sum of its proper divisors (1632315401631).

21220100221021 is a wasteful number, since it uses less digits than its factorization.

21220100221021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1632315401630.

The product of its (nonzero) digits is 64, while the sum is 16.

Adding to 21220100221021 its reverse (12012200102212), we get a palindrome (33232300323233).

The spelling of 21220100221021 in words is "twenty-one trillion, two hundred twenty billion, one hundred million, two hundred twenty-one thousand, twenty-one".