21204241 has 2 divisors, whose sum is σ = 21204242. Its totient is φ = 21204240.

The previous prime is 21204223. The next prime is 21204251. The reversal of 21204241 is 14240212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19395216 + 1809025 = 4404^2 + 1345^2 .

It is a cyclic number.

It is not a de Polignac number, because 21204241 - 2⁹ = 21203729 is a prime.

It is a super-3 number, since 3×21204241³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (21204251) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602120 + 10602121.

It is an arithmetic number, because the mean of its divisors is an integer number (10602121).

Almost surely, 2^21204241 is an apocalyptic number.

It is an amenable number.

21204241 is a deficient number, since it is larger than the sum of its proper divisors (1).

21204241 is an equidigital number, since it uses as much as digits as its factorization.

21204241 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 16.

The square root of 21204241 is about 4604.8062934286. The cubic root of 21204241 is about 276.7839548834.

Adding to 21204241 its reverse (14240212), we get a palindrome (35444453).

It can be divided in two parts, 2120 and 4241, that multiplied together give a triangular number (8990920 = T₄₂₄₀).

The spelling of 21204241 in words is "twenty-one million, two hundred four thousand, two hundred forty-one".