21330013 has 4 divisors (see below), whose sum is σ = 21379708. Its totient is φ = 21280320.

The previous prime is 21329999. The next prime is 21330047. The reversal of 21330013 is 31003312.

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

It can be written as a sum of positive squares in 2 ways, for example, as 4173849 + 17156164 = 2043^2 + 4142^2 .

It is a cyclic number.

It is not a de Polignac number, because 21330013 - 2⁵ = 21329981 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21329975 and 21330002.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21330073) 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 in 3 ways as a sum of consecutive naturals, for example, 24198 + ... + 25063.

It is an arithmetic number, because the mean of its divisors is an integer number (5344927).

Almost surely, 2^21330013 is an apocalyptic number.

It is an amenable number.

21330013 is a deficient number, since it is larger than the sum of its proper divisors (49695).

21330013 is an equidigital number, since it uses as much as digits as its factorization.

21330013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49694.

The product of its (nonzero) digits is 54, while the sum is 13.

The square root of 21330013 is about 4618.4427029032. The cubic root of 21330013 is about 277.3301203028.

Adding to 21330013 its reverse (31003312), we get a palindrome (52333325).

The spelling of 21330013 in words is "twenty-one million, three hundred thirty thousand, thirteen".