21667216 has 20 divisors (see below), whose sum is σ = 42314752. Its totient is φ = 10747296.

The previous prime is 21667211. The next prime is 21667223. The reversal of 21667216 is 61276612.

It is a happy number.

It is a plaindrome in base 11.

It is not an unprimeable number, because it can be changed into a prime (21667211) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 3300 + ... + 7363.

Almost surely, 2^21667216 is an apocalyptic number.

It is an amenable number.

21667216 is a deficient number, since it is larger than the sum of its proper divisors (20647536).

21667216 is a wasteful number, since it uses less digits than its factorization.

21667216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10798 (or 10792 counting only the distinct ones).

The product of its digits is 6048, while the sum is 31.

The square root of 21667216 is about 4654.8056887479. The cubic root of 21667216 is about 278.7839096206.

The spelling of 21667216 in words is "twenty-one million, six hundred sixty-seven thousand, two hundred sixteen".