21133312 has 48 divisors (see below), whose sum is σ = 44815680. Its totient is φ = 9928704.

The previous prime is 21133309. The next prime is 21133381. The reversal of 21133312 is 21333112.

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34513 + ... + 35119.

It is an arithmetic number, because the mean of its divisors is an integer number (933660).

Almost surely, 2^21133312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21133312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22407840).

21133312 is an abundant number, since it is smaller than the sum of its proper divisors (23682368).

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

21133312 is an equidigital number, since it uses as much as digits as its factorization.

21133312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 646 (or 626 counting only the distinct ones).

The product of its digits is 108, while the sum is 16.

The square root of 21133312 is about 4597.0982151788. The cubic root of 21133312 is about 276.4749924790.

Adding to 21133312 its reverse (21333112), we get a palindrome (42466424).

The spelling of 21133312 in words is "twenty-one million, one hundred thirty-three thousand, three hundred twelve".