21303305 has 8 divisors (see below), whose sum is σ = 26255112. Its totient is φ = 16581888.

The previous prime is 21303301. The next prime is 21303311. The reversal of 21303305 is 50330312.

It can be written as a sum of positive squares in 4 ways, for example, as 8479744 + 12823561 = 2912^2 + 3581^2 .

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 21303305 - 2² = 21303301 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21303301) 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 7 ways as a sum of consecutive naturals, for example, 57392 + ... + 57761.

It is an arithmetic number, because the mean of its divisors is an integer number (3281889).

Almost surely, 2^21303305 is an apocalyptic number.

It is an amenable number.

21303305 is a deficient number, since it is larger than the sum of its proper divisors (4951807).

21303305 is a wasteful number, since it uses less digits than its factorization.

21303305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 115195.

The product of its (nonzero) digits is 270, while the sum is 17.

The square root of 21303305 is about 4615.5503463834. The cubic root of 21303305 is about 277.2143206157.

Adding to 21303305 its reverse (50330312), we get a palindrome (71633617).

The spelling of 21303305 in words is "twenty-one million, three hundred three thousand, three hundred five".