21232256 has 16 divisors (see below), whose sum is σ = 42298890. Its totient is φ = 10616064.

The previous prime is 21232249. The next prime is 21232259. The reversal of 21232256 is 65223212.

It can be written as a sum of positive squares in only one way, i.e., 16321600 + 4910656 = 4040^2 + 2216^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a zygodrome in base 4.

It is not an unprimeable number, because it can be changed into a prime (21232259) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 82811 + ... + 83066.

Almost surely, 2^21232256 is an apocalyptic number.

It is an amenable number.

21232256 is a deficient number, since it is larger than the sum of its proper divisors (21066634).

21232256 is an equidigital number, since it uses as much as digits as its factorization.

21232256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 165891 (or 165879 counting only the distinct ones).

The product of its digits is 1440, while the sum is 23.

The square root of 21232256 is about 4607.8472196895. The cubic root of 21232256 is about 276.9057967058.

Adding to 21232256 its reverse (65223212), we get a palindrome (86455468).

The spelling of 21232256 in words is "twenty-one million, two hundred thirty-two thousand, two hundred fifty-six".