21104208 has 120 divisors (see below), whose sum is σ = 64502568. Its totient is φ = 6414336.

The previous prime is 21104203. The next prime is 21104221. The reversal of 21104208 is 80240112.

It can be written as a sum of positive squares in 4 ways, for example, as 6906384 + 14197824 = 2628^2 + 3768^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21104203) 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 23 ways as a sum of consecutive naturals, for example, 90460 + ... + 90692.

Almost surely, 2^21104208 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 21104208, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32251284).

21104208 is an abundant number, since it is smaller than the sum of its proper divisors (43398360).

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

21104208 is a wasteful number, since it uses less digits than its factorization.

21104208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 301 (or 292 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 18.

The square root of 21104208 is about 4593.9316494698. The cubic root of 21104208 is about 276.3480171963.

It can be divided in two parts, 21104 and 208, that added together give a palindrome (21312).

The spelling of 21104208 in words is "twenty-one million, one hundred four thousand, two hundred eight".