21147216 has 20 divisors (see below), whose sum is σ = 54630432. Its totient is φ = 7049056.

The previous prime is 21147211. The next prime is 21147223. The reversal of 21147216 is 61274112.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21147211) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 220236 + ... + 220331.

Almost surely, 2^21147216 is an apocalyptic number.

It is an amenable number.

21147216 is an abundant number, since it is smaller than the sum of its proper divisors (33483216).

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

21147216 is a wasteful number, since it uses less digits than its factorization.

21147216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 440578 (or 440572 counting only the distinct ones).

The product of its digits is 672, while the sum is 24.

The square root of 21147216 is about 4598.6102248397. The cubic root of 21147216 is about 276.5356118709.

The spelling of 21147216 in words is "twenty-one million, one hundred forty-seven thousand, two hundred sixteen".