21336305 has 4 divisors (see below), whose sum is σ = 25603572. Its totient is φ = 17069040.

The previous prime is 21336283. The next prime is 21336307. The reversal of 21336305 is 50363312.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3964081 + 17372224 = 1991^2 + 4168^2 .

It is not a de Polignac number, because 21336305 - 2¹² = 21332209 is a prime.

It is a super-2 number, since 2×21336305² = 910475822106050, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21336307) 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, 2133626 + ... + 2133635.

It is an arithmetic number, because the mean of its divisors is an integer number (6400893).

Almost surely, 2^21336305 is an apocalyptic number.

It is an amenable number.

21336305 is a deficient number, since it is larger than the sum of its proper divisors (4267267).

21336305 is an equidigital number, since it uses as much as digits as its factorization.

21336305 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4267266.

The product of its (nonzero) digits is 1620, while the sum is 23.

The square root of 21336305 is about 4619.1238346682. The cubic root of 21336305 is about 277.3573868835.

Adding to 21336305 its reverse (50363312), we get a palindrome (71699617).

The spelling of 21336305 in words is "twenty-one million, three hundred thirty-six thousand, three hundred five".