21330421 has 4 divisors (see below), whose sum is σ = 24377632. Its totient is φ = 18283212.

The previous prime is 21330403. The next prime is 21330443. The reversal of 21330421 is 12403312.

It is a happy number.

21330421 is nontrivially palindromic in base 15.

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 a cyclic number.

It is not a de Polignac number, because 21330421 - 2⁹ = 21329909 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21330395 and 21330404.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330481) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1523595 + ... + 1523608.

It is an arithmetic number, because the mean of its divisors is an integer number (6094408).

Almost surely, 2^21330421 is an apocalyptic number.

It is an amenable number.

21330421 is a deficient number, since it is larger than the sum of its proper divisors (3047211).

21330421 is an equidigital number, since it uses as much as digits as its factorization.

21330421 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3047210.

The product of its (nonzero) digits is 144, while the sum is 16.

The square root of 21330421 is about 4618.4868734251. The cubic root of 21330421 is about 277.3318885462.

Adding to 21330421 its reverse (12403312), we get a palindrome (33733733).

The spelling of 21330421 in words is "twenty-one million, three hundred thirty thousand, four hundred twenty-one".