21280241 has 2 divisors, whose sum is σ = 21280242. Its totient is φ = 21280240.

The previous prime is 21280223. The next prime is 21280253. The reversal of 21280241 is 14208212.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18318400 + 2961841 = 4280^2 + 1721^2 .

It is a cyclic number.

It is not a de Polignac number, because 21280241 - 2⁶ = 21280177 is a prime.

It is not a weakly prime, because it can be changed into another prime (21280201) 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, 10640120 + 10640121.

It is an arithmetic number, because the mean of its divisors is an integer number (10640121).

Almost surely, 2^21280241 is an apocalyptic number.

It is an amenable number.

21280241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21280241 is an equidigital number, since it uses as much as digits as its factorization.

21280241 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 256, while the sum is 20.

The square root of 21280241 is about 4613.0511594822. The cubic root of 21280241 is about 277.1142425629.

Adding to 21280241 its reverse (14208212), we get a palindrome (35488453).

The spelling of 21280241 in words is "twenty-one million, two hundred eighty thousand, two hundred forty-one".