21304008 has 96 divisors (see below), whose sum is σ = 64733760. Its totient is φ = 6272640.

The previous prime is 21304001. The next prime is 21304027. The reversal of 21304008 is 80040312.

It is a happy number.

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 (21304001) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 28941 + ... + 29667.

It is an arithmetic number, because the mean of its divisors is an integer number (674310).

Almost surely, 2^21304008 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 21304008, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32366880).

21304008 is an abundant number, since it is smaller than the sum of its proper divisors (43429752).

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

21304008 is a wasteful number, since it uses less digits than its factorization.

21304008 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 787 (or 780 counting only the distinct ones).

The product of its (nonzero) digits is 192, while the sum is 18.

The square root of 21304008 is about 4615.6265013539. The cubic root of 21304008 is about 277.2173699003.

The spelling of 21304008 in words is "twenty-one million, three hundred four thousand, eight".