21220013 has 4 divisors (see below), whose sum is σ = 21265920. Its totient is φ = 21174108.

The previous prime is 21219997. The next prime is 21220019. The reversal of 21220013 is 31002212.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21220013 - 2⁴ = 21219997 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21219976 and 21220003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220019) 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, 22253 + ... + 23186.

It is an arithmetic number, because the mean of its divisors is an integer number (5316480).

Almost surely, 2^21220013 is an apocalyptic number.

It is an amenable number.

21220013 is a deficient number, since it is larger than the sum of its proper divisors (45907).

21220013 is an equidigital number, since it uses as much as digits as its factorization.

21220013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45906.

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21220013 is about 4606.5185335566. The cubic root of 21220013 is about 276.8525630866.

Adding to 21220013 its reverse (31002212), we get a palindrome (52222225).

The spelling of 21220013 in words is "twenty-one million, two hundred twenty thousand, thirteen".