21359808 has 112 divisors (see below), whose sum is σ = 64373760. Its totient is φ = 6941952.

The previous prime is 21359797. The next prime is 21359813. The reversal of 21359808 is 80895312.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 81085 + ... + 81347.

Almost surely, 2^21359808 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 21359808, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32186880).

21359808 is an abundant number, since it is smaller than the sum of its proper divisors (43013952).

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

21359808 is a wasteful number, since it uses less digits than its factorization.

21359808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 331 (or 315 counting only the distinct ones).

The product of its (nonzero) digits is 17280, while the sum is 36.

The square root of 21359808 is about 4621.6672316384. The cubic root of 21359808 is about 277.4591904926.

The spelling of 21359808 in words is "twenty-one million, three hundred fifty-nine thousand, eight hundred eight".