21021033020021 has 4 divisors (see below), whose sum is σ = 21111252046092. Its totient is φ = 20930813993952.

The previous prime is 21021033020017. The next prime is 21021033020051. The reversal of 21021033020021 is 12002033012012.

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 14374820119396 + 6646212900625 = 3791414^2 + 2578025^2 .

It is a cyclic number.

It is not a de Polignac number, because 21021033020021 - 2² = 21021033020017 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21021033020011) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 45109512686 + ... + 45109513151.

It is an arithmetic number, because the mean of its divisors is an integer number (5277813011523).

Almost surely, 2^{21021033020021} is an apocalyptic number.

It is an amenable number.

21021033020021 is a deficient number, since it is larger than the sum of its proper divisors (90219026071).

21021033020021 is an equidigital number, since it uses as much as digits as its factorization.

21021033020021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90219026070.

The product of its (nonzero) digits is 144, while the sum is 17.

Adding to 21021033020021 its reverse (12002033012012), we get a palindrome (33023066032033).

The spelling of 21021033020021 in words is "twenty-one trillion, twenty-one billion, thirty-three million, twenty thousand, twenty-one".