21203321 has 8 divisors (see below), whose sum is σ = 22078920. Its totient is φ = 20337408.

The previous prime is 21203317. The next prime is 21203341. The reversal of 21203321 is 12330212.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 144400 + 21058921 = 380^2 + 4589^2 .

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 21203321 - 2² = 21203317 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21203296 and 21203305.

It is not an unprimeable number, because it can be changed into a prime (21203341) 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, 2225 + ... + 6881.

It is an arithmetic number, because the mean of its divisors is an integer number (2759865).

Almost surely, 2^21203321 is an apocalyptic number.

It is an amenable number.

21203321 is a deficient number, since it is larger than the sum of its proper divisors (875599).

21203321 is a wasteful number, since it uses less digits than its factorization.

21203321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4843.

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

The square root of 21203321 is about 4604.7063967206. The cubic root of 21203321 is about 276.7799518333.

Adding to 21203321 its reverse (12330212), we get a palindrome (33533533).

The spelling of 21203321 in words is "twenty-one million, two hundred three thousand, three hundred twenty-one".