21230321 has 8 divisors (see below), whose sum is σ = 24556224. Its totient is φ = 17977680.

The previous prime is 21230309. The next prime is 21230329. The reversal of 21230321 is 12303212.

It is a happy number.

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

It is not a de Polignac number, because 21230321 - 2¹⁰ = 21229297 is a prime.

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

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21230296 and 21230305.

It is not an unprimeable number, because it can be changed into a prime (21230329) 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, 17690 + ... + 18851.

It is an arithmetic number, because the mean of its divisors is an integer number (3069528).

Almost surely, 2^21230321 is an apocalyptic number.

It is an amenable number.

21230321 is a deficient number, since it is larger than the sum of its proper divisors (3325903).

21230321 is an equidigital number, since it uses as much as digits as its factorization.

21230321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36631.

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

The square root of 21230321 is about 4607.6372470063. The cubic root of 21230321 is about 276.8973845209.

Adding to 21230321 its reverse (12303212), we get a palindrome (33533533).

It can be divided in two parts, 2 and 1230321, that multiplied together give a palindrome (2460642).

The spelling of 21230321 in words is "twenty-one million, two hundred thirty thousand, three hundred twenty-one".