21113216 has 32 divisors (see below), whose sum is σ = 42283080. Its totient is φ = 10501120.

The previous prime is 21113173. The next prime is 21113221. The reversal of 21113216 is 61231112.

It is a tau number, because it is divible by the number of its divisors (32).

It is a junction number, because it is equal to n+sod(n) for n = 21113194 and 21113203.

It is a congruent number.

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 3 ways as a sum of consecutive naturals, for example, 35675 + ... + 36261.

Almost surely, 2^21113216 is an apocalyptic number.

It is an amenable number.

21113216 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

21113216 is an equidigital number, since it uses as much as digits as its factorization.

21113216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 882 (or 870 counting only the distinct ones).

The product of its digits is 72, while the sum is 17.

The square root of 21113216 is about 4594.9119686888. The cubic root of 21113216 is about 276.3873298749.

Adding to 21113216 its reverse (61231112), we get a palindrome (82344328).

The spelling of 21113216 in words is "twenty-one million, one hundred thirteen thousand, two hundred sixteen".