21303311 has 2 divisors, whose sum is σ = 21303312. Its totient is φ = 21303310.

The previous prime is 21303301. The next prime is 21303319. The reversal of 21303311 is 11330312.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21303311 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21303319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651655 + 10651656.

It is an arithmetic number, because the mean of its divisors is an integer number (10651656).

Almost surely, 2^21303311 is an apocalyptic number.

21303311 is a deficient number, since it is larger than the sum of its proper divisors (1).

21303311 is an equidigital number, since it uses as much as digits as its factorization.

21303311 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 54, while the sum is 14.

The square root of 21303311 is about 4615.5509963600. The cubic root of 21303311 is about 277.2143466412.

Adding to 21303311 its reverse (11330312), we get a palindrome (32633623).

The spelling of 21303311 in words is "twenty-one million, three hundred three thousand, three hundred eleven".