21221306 has 8 divisors (see below), whose sum is σ = 32432724. Its totient is φ = 10410400.

The previous prime is 21221303. The next prime is 21221339. The reversal of 21221306 is 60312212.

It can be written as a sum of positive squares in 2 ways, for example, as 20620681 + 600625 = 4541^2 + 775^2 .

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

It is not an unprimeable number, because it can be changed into a prime (21221303) 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, 99995 + ... + 100206.

Almost surely, 2^21221306 is an apocalyptic number.

21221306 is a deficient number, since it is larger than the sum of its proper divisors (11211418).

21221306 is a wasteful number, since it uses less digits than its factorization.

21221306 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 200256.

The product of its (nonzero) digits is 144, while the sum is 17.

The square root of 21221306 is about 4606.6588760185. The cubic root of 21221306 is about 276.8581861290.

Adding to 21221306 its reverse (60312212), we get a palindrome (81533518).

The spelling of 21221306 in words is "twenty-one million, two hundred twenty-one thousand, three hundred six".