21331333 has 2 divisors, whose sum is σ = 21331334. Its totient is φ = 21331332.

The previous prime is 21331313. The next prime is 21331339. The reversal of 21331333 is 33313312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14607684 + 6723649 = 3822^2 + 2593^2 .

It is a cyclic number.

It is not a de Polignac number, because 21331333 - 2²¹ = 19234181 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21331333.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21331339) 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 as a sum of consecutive naturals, namely, 10665666 + 10665667.

It is an arithmetic number, because the mean of its divisors is an integer number (10665667).

Almost surely, 2^21331333 is an apocalyptic number.

It is an amenable number.

21331333 is a deficient number, since it is larger than the sum of its proper divisors (1).

21331333 is an equidigital number, since it uses as much as digits as its factorization.

21331333 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 486, while the sum is 19.

The square root of 21331333 is about 4618.5856060054. The cubic root of 21331333 is about 277.3358410089.

Adding to 21331333 its reverse (33313312), we get a palindrome (54644645).

The spelling of 21331333 in words is "twenty-one million, three hundred thirty-one thousand, three hundred thirty-three".