21306133 has 6 divisors (see below), whose sum is σ = 21453014. Its totient is φ = 21160104.

The previous prime is 21306091. The next prime is 21306143. The reversal of 21306133 is 33160312.

It can be written as a sum of positive squares in only one way, i.e., 18507204 + 2798929 = 4302^2 + 1673^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21306133 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 21306133.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21306143) 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 5 ways as a sum of consecutive naturals, for example, 56935 + ... + 57307.

Almost surely, 2^21306133 is an apocalyptic number.

It is an amenable number.

21306133 is a deficient number, since it is larger than the sum of its proper divisors (146881).

21306133 is an frugal number, since it uses more digits than its factorization.

21306133 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 851 (or 612 counting only the distinct ones).

The product of its (nonzero) digits is 324, while the sum is 19.

The square root of 21306133 is about 4615.8566918829. The cubic root of 21306133 is about 277.2265867470.

Adding to 21306133 its reverse (33160312), we get a palindrome (54466445).

The spelling of 21306133 in words is "twenty-one million, three hundred six thousand, one hundred thirty-three".