21563536 has 20 divisors (see below), whose sum is σ = 41961600. Its totient is φ = 10734752.

The previous prime is 21563519. The next prime is 21563539. The reversal of 21563536 is 63536512.

It is a junction number, because it is equal to n+sod(n) for n = 21563498 and 21563507.

It is not an unprimeable number, because it can be changed into a prime (21563539) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1005 + ... + 6643.

It is an arithmetic number, because the mean of its divisors is an integer number (2098080).

Almost surely, 2^21563536 is an apocalyptic number.

It is an amenable number.

21563536 is a deficient number, since it is larger than the sum of its proper divisors (20398064).

21563536 is a wasteful number, since it uses less digits than its factorization.

21563536 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5886 (or 5880 counting only the distinct ones).

The product of its digits is 16200, while the sum is 31.

The square root of 21563536 is about 4643.6554566419. The cubic root of 21563536 is about 278.3385279567.

The spelling of 21563536 in words is "twenty-one million, five hundred sixty-three thousand, five hundred thirty-six".