21236256 has 72 divisors (see below), whose sum is σ = 62650224. Its totient is φ = 7076160.

The previous prime is 21236251. The next prime is 21236263. The reversal of 21236256 is 65263212.

It is a tau number, because it is divible by the number of its divisors (72).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is not an unprimeable number, because it can be changed into a prime (21236251) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 6411 + ... + 9141.

It is an arithmetic number, because the mean of its divisors is an integer number (870142).

Almost surely, 2^21236256 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 21236256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31325112).

21236256 is an abundant number, since it is smaller than the sum of its proper divisors (41413968).

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

21236256 is an equidigital number, since it uses as much as digits as its factorization.

21236256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2756 (or 2736 counting only the distinct ones).

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

The square root of 21236256 is about 4608.2812414175. The cubic root of 21236256 is about 276.9231846153.

Adding to 21236256 its reverse (65263212), we get a palindrome (86499468).

The spelling of 21236256 in words is "twenty-one million, two hundred thirty-six thousand, two hundred fifty-six".