21243216 has 40 divisors (see below), whose sum is σ = 57769120. Its totient is φ = 6708096.

The previous prime is 21243193. The next prime is 21243227. The reversal of 21243216 is 61234212.

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

It is a junction number, because it is equal to n+sod(n) for n = 21243192 and 21243201.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10735 + ... + 12558.

It is an arithmetic number, because the mean of its divisors is an integer number (1444228).

Almost surely, 2^21243216 is an apocalyptic number.

It is an amenable number.

21243216 is an abundant number, since it is smaller than the sum of its proper divisors (36525904).

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

21243216 is a wasteful number, since it uses less digits than its factorization.

21243216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23323 (or 23317 counting only the distinct ones).

The product of its digits is 576, while the sum is 21.

The square root of 21243216 is about 4609.0363417964. The cubic root of 21243216 is about 276.9534343738.

Adding to 21243216 its reverse (61234212), we get a palindrome (82477428).

The spelling of 21243216 in words is "twenty-one million, two hundred forty-three thousand, two hundred sixteen".