21228307 has 2 divisors, whose sum is σ = 21228308. Its totient is φ = 21228306.

The previous prime is 21228289. The next prime is 21228331. The reversal of 21228307 is 70382212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21228307 - 2²³ = 12839699 is a prime.

It is not a weakly prime, because it can be changed into another prime (21228007) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10614153 + 10614154.

It is an arithmetic number, because the mean of its divisors is an integer number (10614154).

Almost surely, 2^21228307 is an apocalyptic number.

21228307 is a deficient number, since it is larger than the sum of its proper divisors (1).

21228307 is an equidigital number, since it uses as much as digits as its factorization.

21228307 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1344, while the sum is 25.

The square root of 21228307 is about 4607.4186916320. The cubic root of 21228307 is about 276.8886283498. Note that the first 3 decimals are identical.

The spelling of 21228307 in words is "twenty-one million, two hundred twenty-eight thousand, three hundred seven".