21063505 has 4 divisors (see below), whose sum is σ = 25276212. Its totient is φ = 16850800.

The previous prime is 21063503. The next prime is 21063517. The reversal of 21063505 is 50536012.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 15992001 + 5071504 = 3999^2 + 2252^2 .

It is not a de Polignac number, because 21063505 - 2¹ = 21063503 is a prime.

It is a Smith number, since the sum of its digits (22) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21063503) 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 in 3 ways as a sum of consecutive naturals, for example, 2106346 + ... + 2106355.

It is an arithmetic number, because the mean of its divisors is an integer number (6319053).

Almost surely, 2^21063505 is an apocalyptic number.

It is an amenable number.

21063505 is a deficient number, since it is larger than the sum of its proper divisors (4212707).

21063505 is an equidigital number, since it uses as much as digits as its factorization.

21063505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4212706.

The product of its (nonzero) digits is 900, while the sum is 22.

The square root of 21063505 is about 4589.4994280422. The cubic root of 21063505 is about 276.1702417112.

Adding to 21063505 its reverse (50536012), we get a palindrome (71599517).

The spelling of 21063505 in words is "twenty-one million, sixty-three thousand, five hundred five".