21945263 has 2 divisors, whose sum is σ = 21945264. Its totient is φ = 21945262.

The previous prime is 21945239. The next prime is 21945271. The reversal of 21945263 is 36254912.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21945263 - 2¹⁰ = 21944239 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21945293) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10972631 + 10972632.

It is an arithmetic number, because the mean of its divisors is an integer number (10972632).

Almost surely, 2^21945263 is an apocalyptic number.

21945263 is a deficient number, since it is larger than the sum of its proper divisors (1).

21945263 is an equidigital number, since it uses as much as digits as its factorization.

21945263 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 12960, while the sum is 32.

The square root of 21945263 is about 4684.5771420695. The cubic root of 21945263 is about 279.9713533618.

The spelling of 21945263 in words is "twenty-one million, nine hundred forty-five thousand, two hundred sixty-three".