21243335 has 4 divisors (see below), whose sum is σ = 25492008. Its totient is φ = 16994664.

The previous prime is 21243331. The next prime is 21243347. The reversal of 21243335 is 53334212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21243335 - 2² = 21243331 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21243335.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243331) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2124329 + ... + 2124338.

It is an arithmetic number, because the mean of its divisors is an integer number (6373002).

Almost surely, 2^21243335 is an apocalyptic number.

21243335 is a deficient number, since it is larger than the sum of its proper divisors (4248673).

21243335 is an equidigital number, since it uses as much as digits as its factorization.

21243335 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4248672.

The product of its digits is 2160, while the sum is 23.

The square root of 21243335 is about 4609.0492512014. The cubic root of 21243335 is about 276.9539515176.

Adding to 21243335 its reverse (53334212), we get a palindrome (74577547).

The spelling of 21243335 in words is "twenty-one million, two hundred forty-three thousand, three hundred thirty-five".