21447216 has 60 divisors (see below), whose sum is σ = 68600272. Its totient is φ = 6127488.

The previous prime is 21447203. The next prime is 21447229. The reversal of 21447216 is 61274412.

21447216 is a `hidden beast` number, since 2 + 1 + 447 + 216 = 666.

It is an interprime number because it is at equal distance from previous prime (21447203) and next prime (21447229).

It is a nude number because it is divisible by every one of its digits.

It is a self number, because there is not a number n which added to its sum of digits gives 21447216.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9631 + ... + 11646.

Almost surely, 2^21447216 is an apocalyptic number.

It is an amenable number.

21447216 is an abundant number, since it is smaller than the sum of its proper divisors (47153056).

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

21447216 is a wasteful number, since it uses less digits than its factorization.

21447216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21298 (or 21289 counting only the distinct ones).

The product of its digits is 2688, while the sum is 27.

The square root of 21447216 is about 4631.1139048829. The cubic root of 21447216 is about 277.8371456159.

The spelling of 21447216 in words is "twenty-one million, four hundred forty-seven thousand, two hundred sixteen".