21363216 has 120 divisors (see below), whose sum is σ = 66495744. Its totient is φ = 5886720.

The previous prime is 21363193. The next prime is 21363253. The reversal of 21363216 is 61236312.

It is a happy number.

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

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

It is a congruent number.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 72766 + ... + 73058.

Almost surely, 2^21363216 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21363216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (33247872).

21363216 is an abundant number, since it is smaller than the sum of its proper divisors (45132528).

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

21363216 is a wasteful number, since it uses less digits than its factorization.

21363216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 349 (or 336 counting only the distinct ones).

The product of its digits is 1296, while the sum is 24.

The square root of 21363216 is about 4622.0359150487. The cubic root of 21363216 is about 277.4739460971.

Adding to 21363216 its reverse (61236312), we get a palindrome (82599528).

The spelling of 21363216 in words is "twenty-one million, three hundred sixty-three thousand, two hundred sixteen".