21518336 has 96 divisors (see below), whose sum is σ = 52416000. Its totient is φ = 8626176.

The previous prime is 21518333. The next prime is 21518347. The reversal of 21518336 is 63381512.

It is a junction number, because it is equal to n+sod(n) for n = 21518299 and 21518308.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21518333) 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, 272345 + ... + 272423.

It is an arithmetic number, because the mean of its divisors is an integer number (546000).

Almost surely, 2^21518336 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 21518336, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26208000).

21518336 is an abundant number, since it is smaller than the sum of its proper divisors (30897664).

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

21518336 is an equidigital number, since it uses as much as digits as its factorization.

21518336 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 127 (or 107 counting only the distinct ones).

The product of its digits is 4320, while the sum is 29.

The square root of 21518336 is about 4638.7860480949. The cubic root of 21518336 is about 278.1439138928.

Adding to 21518336 its reverse (63381512), we get a palindrome (84899848).

The spelling of 21518336 in words is "twenty-one million, five hundred eighteen thousand, three hundred thirty-six".