21243263 has 2 divisors, whose sum is σ = 21243264. Its totient is φ = 21243262.

The previous prime is 21243259. The next prime is 21243293. The reversal of 21243263 is 36234212.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21243263 - 2² = 21243259 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21243253) 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, 10621631 + 10621632.

It is an arithmetic number, because the mean of its divisors is an integer number (10621632).

Almost surely, 2^21243263 is an apocalyptic number.

21243263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21243263 is an equidigital number, since it uses as much as digits as its factorization.

21243263 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 23.

The square root of 21243263 is about 4609.0414404733. The cubic root of 21243263 is about 276.9536386241.

Adding to 21243263 its reverse (36234212), we get a palindrome (57477475).

The spelling of 21243263 in words is "twenty-one million, two hundred forty-three thousand, two hundred sixty-three".