21261241 has 2 divisors, whose sum is σ = 21261242. Its totient is φ = 21261240.

The previous prime is 21261239. The next prime is 21261259. The reversal of 21261241 is 14216212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18455616 + 2805625 = 4296^2 + 1675^2 .

It is a cyclic number.

It is not a de Polignac number, because 21261241 - 2¹ = 21261239 is a prime.

Together with 21261239, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21261211) 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, 10630620 + 10630621.

It is an arithmetic number, because the mean of its divisors is an integer number (10630621).

Almost surely, 2^21261241 is an apocalyptic number.

It is an amenable number.

21261241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21261241 is an equidigital number, since it uses as much as digits as its factorization.

21261241 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 192, while the sum is 19.

The square root of 21261241 is about 4610.9913250840. The cubic root of 21261241 is about 277.0317444624.

Adding to 21261241 its reverse (14216212), we get a palindrome (35477453).

The spelling of 21261241 in words is "twenty-one million, two hundred sixty-one thousand, two hundred forty-one".