21110256 has 60 divisors (see below), whose sum is σ = 60998080. Its totient is φ = 6808320.

The previous prime is 21110249. The next prime is 21110261. The reversal of 21110256 is 65201112.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

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 in 11 ways as a sum of consecutive naturals, for example, 2100 + ... + 6828.

Almost surely, 2^21110256 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 21110256, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30499040).

21110256 is an abundant number, since it is smaller than the sum of its proper divisors (39887824).

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

21110256 is a wasteful number, since it uses less digits than its factorization.

21110256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4774 (or 4765 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 21110256 is about 4594.5898620007. The cubic root of 21110256 is about 276.3744130881.

Adding to 21110256 its reverse (65201112), we get a palindrome (86311368).

The spelling of 21110256 in words is "twenty-one million, one hundred ten thousand, two hundred fifty-six".