21041808 has 80 divisors (see below), whose sum is σ = 57139200. Its totient is φ = 6664320.

The previous prime is 21041807. The next prime is 21041821. The reversal of 21041808 is 80814012.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is not an unprimeable number, because it can be changed into a prime (21041807) 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 15 ways as a sum of consecutive naturals, for example, 117463 + ... + 117641.

It is an arithmetic number, because the mean of its divisors is an integer number (714240).

Almost surely, 2^21041808 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 21041808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28569600).

21041808 is an abundant number, since it is smaller than the sum of its proper divisors (36097392).

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

21041808 is a wasteful number, since it uses less digits than its factorization.

21041808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300 (or 294 counting only the distinct ones).

The product of its (nonzero) digits is 512, while the sum is 24.

The square root of 21041808 is about 4587.1350536037. The cubic root of 21041808 is about 276.0753837354.

The spelling of 21041808 in words is "twenty-one million, forty-one thousand, eight hundred eight".