21304273 has 2 divisors, whose sum is σ = 21304274. Its totient is φ = 21304272.

The previous prime is 21304271. The next prime is 21304277. The reversal of 21304273 is 37240312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15311569 + 5992704 = 3913^2 + 2448^2 .

It is a cyclic number.

It is not a de Polignac number, because 21304273 - 2¹ = 21304271 is a prime.

Together with 21304271, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21304271) 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 as a sum of consecutive naturals, namely, 10652136 + 10652137.

It is an arithmetic number, because the mean of its divisors is an integer number (10652137).

Almost surely, 2^21304273 is an apocalyptic number.

It is an amenable number.

21304273 is a deficient number, since it is larger than the sum of its proper divisors (1).

21304273 is an equidigital number, since it uses as much as digits as its factorization.

21304273 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1008, while the sum is 22.

The square root of 21304273 is about 4615.6552080934. The cubic root of 21304273 is about 277.2185193288.

Adding to 21304273 its reverse (37240312), we get a palindrome (58544585).

The spelling of 21304273 in words is "twenty-one million, three hundred four thousand, two hundred seventy-three".