21210321 has 8 divisors (see below), whose sum is σ = 30851424. Its totient is φ = 12854720.

The previous prime is 21210317. The next prime is 21210337. The reversal of 21210321 is 12301212.

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 21210321 - 2² = 21210317 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a junction number, because it is equal to n+sod(n) for n = 21210297 and 21210306.

It is not an unprimeable number, because it can be changed into a prime (21210221) 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, 321336 + ... + 321401.

It is an arithmetic number, because the mean of its divisors is an integer number (3856428).

Almost surely, 2^21210321 is an apocalyptic number.

It is an amenable number.

21210321 is a deficient number, since it is larger than the sum of its proper divisors (9641103).

21210321 is a wasteful number, since it uses less digits than its factorization.

21210321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 642751.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21210321 is about 4605.4664258900. The cubic root of 21210321 is about 276.8104069130.

Adding to 21210321 its reverse (12301212), we get a palindrome (33511533).

The spelling of 21210321 in words is "twenty-one million, two hundred ten thousand, three hundred twenty-one".