21108233 has 2 divisors, whose sum is σ = 21108234. Its totient is φ = 21108232.

The previous prime is 21108209. The next prime is 21108251. The reversal of 21108233 is 33280112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16386304 + 4721929 = 4048^2 + 2173^2 .

It is a cyclic number.

It is not a de Polignac number, because 21108233 - 2¹⁰ = 21107209 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21108133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10554116 + 10554117.

It is an arithmetic number, because the mean of its divisors is an integer number (10554117).

Almost surely, 2^21108233 is an apocalyptic number.

It is an amenable number.

21108233 is a deficient number, since it is larger than the sum of its proper divisors (1).

21108233 is an equidigital number, since it uses as much as digits as its factorization.

21108233 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 20.

The square root of 21108233 is about 4594.3697064995. The cubic root of 21108233 is about 276.3655844679.

Adding to 21108233 its reverse (33280112), we get a palindrome (54388345).

The spelling of 21108233 in words is "twenty-one million, one hundred eight thousand, two hundred thirty-three".