21403241 has 2 divisors, whose sum is σ = 21403242. Its totient is φ = 21403240.

The previous prime is 21403229. The next prime is 21403243. The reversal of 21403241 is 14230412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11417641 + 9985600 = 3379^2 + 3160^2 .

It is a cyclic number.

It is not a de Polignac number, because 21403241 - 2¹⁰ = 21402217 is a prime.

It is a Sophie Germain prime.

Together with 21403243, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21403243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10701620 + 10701621.

It is an arithmetic number, because the mean of its divisors is an integer number (10701621).

Almost surely, 2^21403241 is an apocalyptic number.

It is an amenable number.

21403241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21403241 is an equidigital number, since it uses as much as digits as its factorization.

21403241 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 192, while the sum is 17.

The square root of 21403241 is about 4626.3636908484. The cubic root of 21403241 is about 277.6471248622.

Adding to 21403241 its reverse (14230412), we get a palindrome (35633653).

The spelling of 21403241 in words is "twenty-one million, four hundred three thousand, two hundred forty-one".