21300305 has 24 divisors (see below), whose sum is σ = 28326312. Its totient is φ = 15282432.

The previous prime is 21300289. The next prime is 21300319. The reversal of 21300305 is 50300312.

21300305 is nontrivially palindromic in base 8.

It can be written as a sum of positive squares in 4 ways, for example, as 543169 + 20757136 = 737^2 + 4556^2 .

It is not a de Polignac number, because 21300305 - 2⁴ = 21300289 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 21300305.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 291749 + ... + 291821.

It is an arithmetic number, because the mean of its divisors is an integer number (1180263).

Almost surely, 2^21300305 is an apocalyptic number.

It is an amenable number.

21300305 is a deficient number, since it is larger than the sum of its proper divisors (7026007).

21300305 is an equidigital number, since it uses as much as digits as its factorization.

21300305 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 225 (or 158 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 14.

The square root of 21300305 is about 4615.2253466109. The cubic root of 21300305 is about 277.2013072671.

Adding to 21300305 its reverse (50300312), we get a palindrome (71600617).

The spelling of 21300305 in words is "twenty-one million, three hundred thousand, three hundred five".