21260243 has 4 divisors (see below), whose sum is σ = 21529440. Its totient is φ = 20991048.

The previous prime is 21260233. The next prime is 21260273. The reversal of 21260243 is 34206212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21260243 - 2⁴ = 21260227 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21260233) 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 in 3 ways as a sum of consecutive naturals, for example, 134480 + ... + 134637.

It is an arithmetic number, because the mean of its divisors is an integer number (5382360).

Almost surely, 2^21260243 is an apocalyptic number.

21260243 is a deficient number, since it is larger than the sum of its proper divisors (269197).

21260243 is an equidigital number, since it uses as much as digits as its factorization.

21260243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 269196.

The product of its (nonzero) digits is 576, while the sum is 20.

The square root of 21260243 is about 4610.8831041353. The cubic root of 21260243 is about 277.0274097827.

Adding to 21260243 its reverse (34206212), we get a palindrome (55466455).

The spelling of 21260243 in words is "twenty-one million, two hundred sixty thousand, two hundred forty-three".