21220216 has 32 divisors (see below), whose sum is σ = 42344640. Its totient is φ = 9934848.

The previous prime is 21220211. The next prime is 21220219. The reversal of 21220216 is 61202212.

It is a self number, because there is not a number n which added to its sum of digits gives 21220216.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21220211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45601 + ... + 46063.

It is an arithmetic number, because the mean of its divisors is an integer number (1323270).

Almost surely, 2^21220216 is an apocalyptic number.

It is an amenable number.

21220216 is a deficient number, since it is larger than the sum of its proper divisors (21124424).

21220216 is a wasteful number, since it uses less digits than its factorization.

21220216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 823 (or 819 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 21220216 is about 4606.5405674975. The cubic root of 21220216 is about 276.8534459150.

Adding to 21220216 its reverse (61202212), we get a palindrome (82422428).

The spelling of 21220216 in words is "twenty-one million, two hundred twenty thousand, two hundred sixteen".