21136 has 10 divisors (see below), whose sum is σ = 40982. Its totient is φ = 10560.

The previous prime is 21121. The next prime is 21139. The reversal of 21136 is 63112.

It can be written as a sum of positive squares in only one way, i.e., 20736 + 400 = 144^2 + 20^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21139) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 645 + ... + 676.

2²¹¹³⁶ is an apocalyptic number.

It is an amenable number.

21136 is a deficient number, since it is larger than the sum of its proper divisors (19846).

21136 is a wasteful number, since it uses less digits than its factorization.

21136 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1329 (or 1323 counting only the distinct ones).

The product of its digits is 36, while the sum is 13.

The square root of 21136 is about 145.3822547631. The cubic root of 21136 is about 27.6486713836.

Adding to 21136 its reverse (63112), we get a palindrome (84248).

The spelling of 21136 in words is "twenty-one thousand, one hundred thirty-six".