21226 has 4 divisors (see below), whose sum is σ = 31842. Its totient is φ = 10612.

The previous prime is 21221. The next prime is 21227. The reversal of 21226 is 62212.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 11025 + 10201 = 105^2 + 101^2 .

It is a Smith number, since the sum of its digits (13) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (21221) by changing a digit.

21226 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 5305 + ... + 5308.

2²¹²²⁶ is an apocalyptic number.

21226 is a deficient number, since it is larger than the sum of its proper divisors (10616).

21226 is a wasteful number, since it uses less digits than its factorization.

21226 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10615.

The product of its digits is 48, while the sum is 13.

The square root of 21226 is about 145.6914547940. The cubic root of 21226 is about 27.6878597636.

Adding to 21226 its reverse (62212), we get a palindrome (83438).

The spelling of 21226 in words is "twenty-one thousand, two hundred twenty-six".