21033133021 has 4 divisors (see below), whose sum is σ = 21758413500. Its totient is φ = 20307852544.

The previous prime is 21033133001. The next prime is 21033133039. The reversal of 21033133021 is 12033133012.

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 12980044900 + 8053088121 = 113930^2 + 89739^2 .

It is a cyclic number.

It is not a de Polignac number, because 21033133021 - 2¹¹ = 21033130973 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21033133021.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033133001) 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, 362640196 + ... + 362640253.

It is an arithmetic number, because the mean of its divisors is an integer number (5439603375).

Almost surely, 2^21033133021 is an apocalyptic number.

It is an amenable number.

21033133021 is a deficient number, since it is larger than the sum of its proper divisors (725280479).

21033133021 is an equidigital number, since it uses as much as digits as its factorization.

21033133021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 725280478.

The product of its (nonzero) digits is 324, while the sum is 19.

Adding to 21033133021 its reverse (12033133012), we get a palindrome (33066266033).

Subtracting from 21033133021 its reverse (12033133012), we obtain a palindrome (9000000009).

The spelling of 21033133021 in words is "twenty-one billion, thirty-three million, one hundred thirty-three thousand, twenty-one".