21208 has 16 divisors (see below), whose sum is σ = 43560. Its totient is φ = 9600.

The previous prime is 21193. The next prime is 21211. The reversal of 21208 is 80212.

It is a plaindrome in base 7.

It is a nialpdrome in base 13.

It is a zygodrome in base 7.

It is a congruent number.

It is an unprimeable number.

21208 is an untouchable number, because it is not equal to the sum of proper divisors of any 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 3 ways as a sum of consecutive naturals, for example, 33 + ... + 208.

2²¹²⁰⁸ is an apocalyptic number.

It is an amenable number.

21208 is an abundant number, since it is smaller than the sum of its proper divisors (22352).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21780).

21208 is a wasteful number, since it uses less digits than its factorization.

21208 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258 (or 254 counting only the distinct ones).

The product of its (nonzero) digits is 32, while the sum is 13.

The square root of 21208 is about 145.6296673072. The cubic root of 21208 is about 27.6800309621.

The spelling of 21208 in words is "twenty-one thousand, two hundred eight".