21221330 has 48 divisors (see below), whose sum is σ = 42887880. Its totient is φ = 7547904.

The previous prime is 21221303. The next prime is 21221339. The reversal of 21221330 is 3312212.

It is a happy number.

It can be written as a sum of positive squares in 12 ways, for example, as 1605289 + 19616041 = 1267^2 + 4429^2 .

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21221339) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 48794 + ... + 49226.

Almost surely, 2^21221330 is an apocalyptic number.

21221330 is an abundant number, since it is smaller than the sum of its proper divisors (21666550).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21221330 is a wasteful number, since it uses less digits than its factorization.

21221330 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 495 (or 482 counting only the distinct ones).

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

The square root of 21221330 is about 4606.6614809426. The cubic root of 21221330 is about 276.8582904988.

Adding to 21221330 its reverse (3312212), we get a palindrome (24533542).

The spelling of 21221330 in words is "twenty-one million, two hundred twenty-one thousand, three hundred thirty".