21005333 has 4 divisors (see below), whose sum is σ = 21017388. Its totient is φ = 20993280.

The previous prime is 21005329. The next prime is 21005339. The reversal of 21005333 is 33350012.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 10609 + 20994724 = 103^2 + 4582^2 .

It is a cyclic number.

It is not a de Polignac number, because 21005333 - 2² = 21005329 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21005339) by changing a digit.

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, 2858 + ... + 7083.

It is an arithmetic number, because the mean of its divisors is an integer number (5254347).

Almost surely, 2^21005333 is an apocalyptic number.

It is an amenable number.

21005333 is a deficient number, since it is larger than the sum of its proper divisors (12055).

21005333 is an equidigital number, since it uses as much as digits as its factorization.

21005333 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12054.

The product of its (nonzero) digits is 270, while the sum is 17.

The square root of 21005333 is about 4583.1575360225. The cubic root of 21005333 is about 275.9157701735.

Adding to 21005333 its reverse (33350012), we get a palindrome (54355345).

The spelling of 21005333 in words is "twenty-one million, five thousand, three hundred thirty-three".