21063808 has 48 divisors (see below), whose sum is σ = 43444350. Its totient is φ = 10171392.

The previous prime is 21063803. The next prime is 21063817. The reversal of 21063808 is 80836012.

It can be written as a sum of positive squares in only one way, i.e., 19998784 + 1065024 = 4472^2 + 1032^2 .

It is not an unprimeable number, because it can be changed into a prime (21063803) 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 5 ways as a sum of consecutive naturals, for example, 236628 + ... + 236716.

Almost surely, 2^21063808 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 21063808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21722175).

21063808 is an abundant number, since it is smaller than the sum of its proper divisors (22380542).

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

21063808 is an frugal number, since it uses more digits than its factorization.

21063808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 189 (or 134 counting only the distinct ones).

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 21063808 is about 4589.5324380595. The cubic root of 21063808 is about 276.1715659476.

The spelling of 21063808 in words is "twenty-one million, sixty-three thousand, eight hundred eight".