21113231 has 2 divisors, whose sum is σ = 21113232. Its totient is φ = 21113230.

The previous prime is 21113221. The next prime is 21113243. The reversal of 21113231 is 13231112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21113231 - 2¹⁰ = 21112207 is a prime.

It is a super-2 number, since 2×21113231² = 891537046518722, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21113221) 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, 10556615 + 10556616.

It is an arithmetic number, because the mean of its divisors is an integer number (10556616).

Almost surely, 2^21113231 is an apocalyptic number.

21113231 is a deficient number, since it is larger than the sum of its proper divisors (1).

21113231 is an equidigital number, since it uses as much as digits as its factorization.

21113231 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 36, while the sum is 14.

The square root of 21113231 is about 4594.9136009287. The cubic root of 21113231 is about 276.3873953286.

Adding to 21113231 its reverse (13231112), we get a palindrome (34344343).

The spelling of 21113231 in words is "twenty-one million, one hundred thirteen thousand, two hundred thirty-one".