21200321 has 4 divisors (see below), whose sum is σ = 21717444. Its totient is φ = 20683200.

The previous prime is 21200303. The next prime is 21200329. The reversal of 21200321 is 12300212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9394225 + 11806096 = 3065^2 + 3436^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21200321 is a prime.

It is a super-2 number, since 2×21200321² = 898907221006082, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21200329) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 258500 + ... + 258581.

It is an arithmetic number, because the mean of its divisors is an integer number (5429361).

Almost surely, 2^21200321 is an apocalyptic number.

It is an amenable number.

21200321 is a deficient number, since it is larger than the sum of its proper divisors (517123).

21200321 is an equidigital number, since it uses as much as digits as its factorization.

21200321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 517122.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21200321 is about 4604.3806315291. The cubic root of 21200321 is about 276.7668976043.

Adding to 21200321 its reverse (12300212), we get a palindrome (33500533).

The spelling of 21200321 in words is "twenty-one million, two hundred thousand, three hundred twenty-one".