21008800 has 36 divisors (see below), whose sum is σ = 51289686. Its totient is φ = 8403200.

The previous prime is 21008797. The next prime is 21008833. The reversal of 21008800 is 880012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 8363664 + 12645136 = 2892^2 + 3556^2 .

It is an unprimeable number.

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 5 ways as a sum of consecutive naturals, for example, 12331 + ... + 13930.

Almost surely, 2^21008800 is an apocalyptic number.

21008800 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21008800 is an abundant number, since it is smaller than the sum of its proper divisors (30280886).

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

21008800 is a wasteful number, since it uses less digits than its factorization.

21008800 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26281 (or 26268 counting only the distinct ones).

The product of its (nonzero) digits is 128, while the sum is 19.

The square root of 21008800 is about 4583.5357531059. The cubic root of 21008800 is about 275.9309496099.

Adding to 21008800 its reverse (880012), we get a palindrome (21888812).

The spelling of 21008800 in words is "twenty-one million, eight thousand, eight hundred".