21204641 has 2 divisors, whose sum is σ = 21204642. Its totient is φ = 21204640.

The previous prime is 21204619. The next prime is 21204679. The reversal of 21204641 is 14640212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13476241 + 7728400 = 3671^2 + 2780^2 .

It is a cyclic number.

It is not a de Polignac number, because 21204641 - 2²² = 17010337 is a prime.

It is not a weakly prime, because it can be changed into another prime (21204241) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10602320 + 10602321.

It is an arithmetic number, because the mean of its divisors is an integer number (10602321).

Almost surely, 2^21204641 is an apocalyptic number.

It is an amenable number.

21204641 is a deficient number, since it is larger than the sum of its proper divisors (1).

21204641 is an equidigital number, since it uses as much as digits as its factorization.

21204641 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 384, while the sum is 20.

The square root of 21204641 is about 4604.8497261040. The cubic root of 21204641 is about 276.7856953039.

Adding to 21204641 its reverse (14640212), we get a palindrome (35844853).

The spelling of 21204641 in words is "twenty-one million, two hundred four thousand, six hundred forty-one".