21563136 has 162 divisors, whose sum is σ = 72700992. Its totient is φ = 6128640.

The previous prime is 21563117. The next prime is 21563137. The reversal of 21563136 is 63136512.

21563136 is a `hidden beast` number, since 21 + 5 + 631 + 3 + 6 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21563137) 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 17 ways as a sum of consecutive naturals, for example, 112801 + ... + 112991.

Almost surely, 2^21563136 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21563136, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36350496).

21563136 is an abundant number, since it is smaller than the sum of its proper divisors (51137856).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21563136 is a wasteful number, since it uses less digits than its factorization.

21563136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 227 (or 203 counting only the distinct ones).

The product of its digits is 3240, while the sum is 27.

The square root of 21563136 is about 4643.6123869246. The cubic root of 21563136 is about 278.3368069016.

Adding to 21563136 its reverse (63136512), we get a palindrome (84699648).

The spelling of 21563136 in words is "twenty-one million, five hundred sixty-three thousand, one hundred thirty-six".