21033221 has 8 divisors (see below), whose sum is σ = 23685888. Its totient is φ = 18504000.

The previous prime is 21033203. The next prime is 21033223. The reversal of 21033221 is 12233012.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21033221 - 2¹⁰ = 21032197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21033196 and 21033205.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21033223) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 30500 + ... + 31181.

It is an arithmetic number, because the mean of its divisors is an integer number (2960736).

Almost surely, 2^21033221 is an apocalyptic number.

It is an amenable number.

21033221 is a deficient number, since it is larger than the sum of its proper divisors (2652667).

21033221 is a wasteful number, since it uses less digits than its factorization.

21033221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 61723.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21033221 is about 4586.1989708254. The cubic root of 21033221 is about 276.0378238788.

Adding to 21033221 its reverse (12233012), we get a palindrome (33266233).

The spelling of 21033221 in words is "twenty-one million, thirty-three thousand, two hundred twenty-one".