21236 has 6 divisors (see below), whose sum is σ = 37170. Its totient is φ = 10616.

The previous prime is 21227. The next prime is 21247. The reversal of 21236 is 63212.

It can be written as a sum of positive squares in only one way, i.e., 11236 + 10000 = 106^2 + 100^2 .

It is a d-powerful number, because it can be written as 2⁷ + 1 + 2⁷ + 3⁹ + 6⁴ .

It is an alternating number because its digits alternate between even and odd.

It is a nialpdrome in base 13.

It is a self number, because there is not a number n which added to its sum of digits gives 21236.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2651 + ... + 2658.

It is an arithmetic number, because the mean of its divisors is an integer number (6195).

2²¹²³⁶ is an apocalyptic number.

It is an amenable number.

21236 is a deficient number, since it is larger than the sum of its proper divisors (15934).

21236 is a wasteful number, since it uses less digits than its factorization.

21236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5313 (or 5311 counting only the distinct ones).

The product of its digits is 72, while the sum is 14.

The square root of 21236 is about 145.7257698556. The cubic root of 21236 is about 27.6922071855.

Adding to 21236 its reverse (63212), we get a palindrome (84448).

The spelling of 21236 in words is "twenty-one thousand, two hundred thirty-six".