21112216 has 16 divisors (see below), whose sum is σ = 39849840. Its totient is φ = 10485600.

The previous prime is 21112207. The next prime is 21112241. The reversal of 21112216 is 61221112.

It is a self number, because there is not a number n which added to its sum of digits gives 21112216.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7531 + ... + 9946.

It is an arithmetic number, because the mean of its divisors is an integer number (2490615).

Almost surely, 2^21112216 is an apocalyptic number.

It is an amenable number.

21112216 is a deficient number, since it is larger than the sum of its proper divisors (18737624).

21112216 is a wasteful number, since it uses less digits than its factorization.

21112216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17634 (or 17630 counting only the distinct ones).

The product of its digits is 48, while the sum is 16.

The square root of 21112216 is about 4594.8031513874. The cubic root of 21112216 is about 276.3829662307.

Adding to 21112216 its reverse (61221112), we get a palindrome (82333328).

The spelling of 21112216 in words is "twenty-one million, one hundred twelve thousand, two hundred sixteen".