21563225 has 24 divisors (see below), whose sum is σ = 28625400. Its totient is φ = 16056320.

The previous prime is 21563219. The next prime is 21563237. The reversal of 21563225 is 52236512.

It can be written as a sum of positive squares in 12 ways, for example, as 8042896 + 13520329 = 2836^2 + 3677^2 .

It is not a de Polignac number, because 21563225 - 2⁶ = 21563161 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21563194 and 21563203.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 47801 + ... + 48249.

It is an arithmetic number, because the mean of its divisors is an integer number (1192725).

Almost surely, 2^21563225 is an apocalyptic number.

21563225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21563225 is a deficient number, since it is larger than the sum of its proper divisors (7062175).

21563225 is a wasteful number, since it uses less digits than its factorization.

21563225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 589 (or 584 counting only the distinct ones).

The product of its digits is 3600, while the sum is 26.

The square root of 21563225 is about 4643.6219699713. The cubic root of 21563225 is about 278.3371898382.

Adding to 21563225 its reverse (52236512), we get a palindrome (73799737).

The spelling of 21563225 in words is "twenty-one million, five hundred sixty-three thousand, two hundred twenty-five".