21024256 has 40 divisors (see below), whose sum is σ = 45838584. Its totient is φ = 9553920.

The previous prime is 21024253. The next prime is 21024259. The reversal of 21024256 is 65242012.

It is an interprime number because it is at equal distance from previous prime (21024253) and next prime (21024259).

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21024253) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3766 + ... + 7498.

Almost surely, 2^21024256 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 21024256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22919292).

21024256 is an abundant number, since it is smaller than the sum of its proper divisors (24814328).

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

21024256 is an equidigital number, since it uses as much as digits as its factorization.

21024256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3762 (or 3746 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 22.

The square root of 21024256 is about 4585.2214777478. The cubic root of 21024256 is about 275.9985997268.

Adding to 21024256 its reverse (65242012), we get a palindrome (86266268).

The spelling of 21024256 in words is "twenty-one million, twenty-four thousand, two hundred fifty-six".