21226356 has 72 divisors (see below), whose sum is σ = 55999944. Its totient is φ = 6773760.

The previous prime is 21226327. The next prime is 21226367. The reversal of 21226356 is 65362212.

21226356 is a `hidden beast` number, since 2 + 1 + 22 + 635 + 6 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 4284900 + 16941456 = 2070^2 + 4116^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 107650 + ... + 107846.

It is an arithmetic number, because the mean of its divisors is an integer number (777777).

Almost surely, 2^21226356 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 21226356, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (27999972).

21226356 is an abundant number, since it is smaller than the sum of its proper divisors (34773588).

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

21226356 is a wasteful number, since it uses less digits than its factorization.

21226356 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321 (or 316 counting only the distinct ones).

The product of its digits is 4320, while the sum is 27.

The square root of 21226356 is about 4607.2069630092. The cubic root of 21226356 is about 276.8801455527.

Adding to 21226356 its reverse (65362212), we get a palindrome (86588568).

The spelling of 21226356 in words is "twenty-one million, two hundred twenty-six thousand, three hundred fifty-six".