21033021 has 8 divisors (see below), whose sum is σ = 28067104. Its totient is φ = 14010480.

The previous prime is 21033011. The next prime is 21033053. The reversal of 21033021 is 12033012.

It is a happy number.

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

It is not a de Polignac number, because 21033021 - 2¹¹ = 21030973 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21032988 and 21033006.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3210 + ... + 7236.

It is an arithmetic number, because the mean of its divisors is an integer number (3508388).

Almost surely, 2^21033021 is an apocalyptic number.

It is an amenable number.

21033021 is a deficient number, since it is larger than the sum of its proper divisors (7034083).

21033021 is a wasteful number, since it uses less digits than its factorization.

21033021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5771.

The product of its (nonzero) digits is 36, while the sum is 12.

The square root of 21033021 is about 4586.1771662246. The cubic root of 21033021 is about 276.0369489496.

Adding to 21033021 its reverse (12033012), we get a palindrome (33066033).

Subtracting from 21033021 its reverse (12033012), we obtain a palindrome (9000009).

The spelling of 21033021 in words is "twenty-one million, thirty-three thousand, twenty-one".