21506041 has 2 divisors, whose sum is σ = 21506042. Its totient is φ = 21506040.

The previous prime is 21506039. The next prime is 21506059. The reversal of 21506041 is 14060512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21427641 + 78400 = 4629^2 + 280^2 .

It is a cyclic number.

It is not a de Polignac number, because 21506041 - 2¹ = 21506039 is a prime.

Together with 21506039, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (21506011) 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, 10753020 + 10753021.

It is an arithmetic number, because the mean of its divisors is an integer number (10753021).

Almost surely, 2^21506041 is an apocalyptic number.

It is an amenable number.

21506041 is a deficient number, since it is larger than the sum of its proper divisors (1).

21506041 is an equidigital number, since it uses as much as digits as its factorization.

21506041 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 19.

The square root of 21506041 is about 4637.4606197789. The cubic root of 21506041 is about 278.0909291429.

Adding to 21506041 its reverse (14060512), we get a palindrome (35566553).

The spelling of 21506041 in words is "twenty-one million, five hundred six thousand, forty-one".