21124309 has 8 divisors (see below), whose sum is σ = 21818720. Its totient is φ = 20439216.

The previous prime is 21124289. The next prime is 21124321. The reversal of 21124309 is 90342112.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21124309 - 2⁵ = 21124277 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 21124309.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21124339) 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 7 ways as a sum of consecutive naturals, for example, 2434 + ... + 6940.

It is an arithmetic number, because the mean of its divisors is an integer number (2727340).

Almost surely, 2^21124309 is an apocalyptic number.

It is an amenable number.

21124309 is a deficient number, since it is larger than the sum of its proper divisors (694411).

21124309 is a wasteful number, since it uses less digits than its factorization.

21124309 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4659.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21124309 is about 4596.1189062077. The cubic root of 21124309 is about 276.4357265419.

The spelling of 21124309 in words is "twenty-one million, one hundred twenty-four thousand, three hundred nine".