21303709 has 4 divisors (see below), whose sum is σ = 24347104. Its totient is φ = 18260316.

The previous prime is 21303707. The next prime is 21303713. The reversal of 21303709 is 90730312.

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 21303709 - 2¹ = 21303707 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21303707) 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 3 ways as a sum of consecutive naturals, for example, 1521687 + ... + 1521700.

It is an arithmetic number, because the mean of its divisors is an integer number (6086776).

Almost surely, 2^21303709 is an apocalyptic number.

It is an amenable number.

21303709 is a deficient number, since it is larger than the sum of its proper divisors (3043395).

21303709 is an equidigital number, since it uses as much as digits as its factorization.

21303709 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3043394.

The product of its (nonzero) digits is 1134, while the sum is 25.

The square root of 21303709 is about 4615.5941112711. The cubic root of 21303709 is about 277.2160729866.

The spelling of 21303709 in words is "twenty-one million, three hundred three thousand, seven hundred nine".