21288216 has 32 divisors (see below), whose sum is σ = 56352240. Its totient is φ = 6678528.

The previous prime is 21288193. The next prime is 21288217. The reversal of 21288216 is 61288212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21288217) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25681 + ... + 26496.

Almost surely, 2^21288216 is an apocalyptic number.

It is an amenable number.

21288216 is an abundant number, since it is smaller than the sum of its proper divisors (35064024).

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

21288216 is a wasteful number, since it uses less digits than its factorization.

21288216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 52203 (or 52199 counting only the distinct ones).

The product of its digits is 3072, while the sum is 30.

The square root of 21288216 is about 4613.9154738682. The cubic root of 21288216 is about 277.1488554239.

The spelling of 21288216 in words is "twenty-one million, two hundred eighty-eight thousand, two hundred sixteen".