21303533 has 16 divisors (see below), whose sum is σ = 23354496. Its totient is φ = 19353600.

The previous prime is 21303523. The next prime is 21303571. The reversal of 21303533 is 33530312.

It is a cyclic number.

It is not a de Polignac number, because 21303533 - 2¹⁰ = 21302509 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 (21303523) 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 15 ways as a sum of consecutive naturals, for example, 110285 + ... + 110477.

It is an arithmetic number, because the mean of its divisors is an integer number (1459656).

Almost surely, 2^21303533 is an apocalyptic number.

It is an amenable number.

21303533 is a deficient number, since it is larger than the sum of its proper divisors (2050963).

21303533 is a wasteful number, since it uses less digits than its factorization.

21303533 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 404.

The product of its (nonzero) digits is 810, while the sum is 20.

The square root of 21303533 is about 4615.5750454304. The cubic root of 21303533 is about 277.2153095802.

Adding to 21303533 its reverse (33530312), we get a palindrome (54833845).

The spelling of 21303533 in words is "twenty-one million, three hundred three thousand, five hundred thirty-three".