21003321 has 4 divisors (see below), whose sum is σ = 28004432. Its totient is φ = 14002212.

The previous prime is 21003299. The next prime is 21003329. The reversal of 21003321 is 12330012.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 21003321 - 2¹³ = 20995129 is a prime.

It is a super-2 number, since 2×21003321² = 882278986058082, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21003297 and 21003306.

It is not an unprimeable number, because it can be changed into a prime (21003329) 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 3 ways as a sum of consecutive naturals, for example, 3500551 + ... + 3500556.

It is an arithmetic number, because the mean of its divisors is an integer number (7001108).

Almost surely, 2^21003321 is an apocalyptic number.

It is an amenable number.

21003321 is a deficient number, since it is larger than the sum of its proper divisors (7001111).

21003321 is an equidigital number, since it uses as much as digits as its factorization.

21003321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7001110.

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

The square root of 21003321 is about 4582.9380314379. The cubic root of 21003321 is about 275.9069603433.

Adding to 21003321 its reverse (12330012), we get a palindrome (33333333).

The spelling of 21003321 in words is "twenty-one million, three thousand, three hundred twenty-one".