21041856 has 196 divisors, whose sum is σ = 69960744. Its totient is φ = 6220800.

The previous prime is 21041827. The next prime is 21041857. The reversal of 21041856 is 65814012.

21041856 is nontrivially palindromic in base 7.

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

It is not an unprimeable number, because it can be changed into a prime (21041857) 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 27 ways as a sum of consecutive naturals, for example, 513196 + ... + 513236.

Almost surely, 2^21041856 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 21041856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34980372).

21041856 is an abundant number, since it is smaller than the sum of its proper divisors (48918888).

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

21041856 is an equidigital number, since it uses as much as digits as its factorization.

21041856 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 82 (or 57 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 21041856 is about 4587.1402856246. The cubic root of 21041856 is about 276.0755936605.

Adding to 21041856 its reverse (65814012), we get a palindrome (86855868).

The spelling of 21041856 in words is "twenty-one million, forty-one thousand, eight hundred fifty-six".