21318016 has 32 divisors (see below), whose sum is σ = 43941600. Its totient is φ = 10289664.

The previous prime is 21318007. The next prime is 21318047. The reversal of 21318016 is 61081312.

It is a tau number, because it is divible by the number of its divisors (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 841 + ... + 6583.

It is an arithmetic number, because the mean of its divisors is an integer number (1373175).

Almost surely, 2^21318016 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 21318016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21970800).

21318016 is an abundant number, since it is smaller than the sum of its proper divisors (22623584).

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

21318016 is an equidigital number, since it uses as much as digits as its factorization.

21318016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5786 (or 5774 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 21318016 is about 4617.1437057991. The cubic root of 21318016 is about 277.2781160615.

Adding to 21318016 its reverse (61081312), we get a palindrome (82399328).

The spelling of 21318016 in words is "twenty-one million, three hundred eighteen thousand, sixteen".