21560256 has 70 divisors (see below), whose sum is σ = 63926720. Its totient is φ = 7185024.

The previous prime is 21560251. The next prime is 21560291. The reversal of 21560256 is 65206512.

21560256 is a `hidden beast` number, since 2 + 1 + 5 + 602 + 56 = 666.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21560251) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 3105 + ... + 7263.

Almost surely, 2^21560256 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 21560256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31963360).

21560256 is an abundant number, since it is smaller than the sum of its proper divisors (42366464).

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

21560256 is an equidigital number, since it uses as much as digits as its factorization.

21560256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4183 (or 4164 counting only the distinct ones).

The product of its (nonzero) digits is 3600, while the sum is 27.

The square root of 21560256 is about 4643.3022731672. The cubic root of 21560256 is about 278.3244146767.

Adding to 21560256 its reverse (65206512), we get a palindrome (86766768).

The spelling of 21560256 in words is "twenty-one million, five hundred sixty thousand, two hundred fifty-six".