21321263 has 2 divisors, whose sum is σ = 21321264. Its totient is φ = 21321262.

The previous prime is 21321217. The next prime is 21321277. The reversal of 21321263 is 36212312.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21321263 - 2⁶ = 21321199 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21321203) 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, 10660631 + 10660632.

It is an arithmetic number, because the mean of its divisors is an integer number (10660632).

Almost surely, 2^21321263 is an apocalyptic number.

21321263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21321263 is an equidigital number, since it uses as much as digits as its factorization.

21321263 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 432, while the sum is 20.

The square root of 21321263 is about 4617.4953167275. The cubic root of 21321263 is about 277.2921929865.

Adding to 21321263 its reverse (36212312), we get a palindrome (57533575).

The spelling of 21321263 in words is "twenty-one million, three hundred twenty-one thousand, two hundred sixty-three".