21384256 has 28 divisors (see below), whose sum is σ = 43076368. Its totient is φ = 10530432.

The previous prime is 21384241. The next prime is 21384257. The reversal of 21384256 is 65248312.

It is not an unprimeable number, because it can be changed into a prime (21384257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1795 + ... + 6781.

Almost surely, 2^21384256 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 21384256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21538184).

21384256 is an abundant number, since it is smaller than the sum of its proper divisors (21692112).

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

21384256 is an equidigital number, since it uses as much as digits as its factorization.

21384256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5066 (or 5056 counting only the distinct ones).

The product of its digits is 11520, while the sum is 31.

The square root of 21384256 is about 4624.3114081991. The cubic root of 21384256 is about 277.5650081715.

The spelling of 21384256 in words is "twenty-one million, three hundred eighty-four thousand, two hundred fifty-six".