21063521 has 2 divisors, whose sum is σ = 21063522. Its totient is φ = 21063520.

The previous prime is 21063517. The next prime is 21063529. The reversal of 21063521 is 12536012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16289296 + 4774225 = 4036^2 + 2185^2 .

It is a cyclic number.

It is not a de Polignac number, because 21063521 - 2² = 21063517 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 21063493 and 21063502.

It is not a weakly prime, because it can be changed into another prime (21063529) 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, 10531760 + 10531761.

It is an arithmetic number, because the mean of its divisors is an integer number (10531761).

Almost surely, 2^21063521 is an apocalyptic number.

It is an amenable number.

21063521 is a deficient number, since it is larger than the sum of its proper divisors (1).

21063521 is an equidigital number, since it uses as much as digits as its factorization.

21063521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 21063521 is about 4589.5011711514. The cubic root of 21063521 is about 276.1703116382.

Adding to 21063521 its reverse (12536012), we get a palindrome (33599533).

The spelling of 21063521 in words is "twenty-one million, sixty-three thousand, five hundred twenty-one".