21103009 has 4 divisors (see below), whose sum is σ = 21116160. Its totient is φ = 21089860.

The previous prime is 21103003. The next prime is 21103021. The reversal of 21103009 is 90030112.

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 a de Polignac number, because none of the positive numbers 2^k-21103009 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21102983 and 21103001.

It is not an unprimeable number, because it can be changed into a prime (21103003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3769 + ... + 7510.

It is an arithmetic number, because the mean of its divisors is an integer number (5279040).

Almost surely, 2^21103009 is an apocalyptic number.

It is an amenable number.

21103009 is a deficient number, since it is larger than the sum of its proper divisors (13151).

21103009 is a wasteful number, since it uses less digits than its factorization.

21103009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13150.

The product of its (nonzero) digits is 54, while the sum is 16.

The square root of 21103009 is about 4593.8011493751. The cubic root of 21103009 is about 276.3427836816.

It can be divided in two parts, 2 and 1103009, that added together give a palindrome (1103011).

The spelling of 21103009 in words is "twenty-one million, one hundred three thousand, nine".