21616384 has 36 divisors (see below), whose sum is σ = 45695664. Its totient is φ = 10170368.

The previous prime is 21616373. The next prime is 21616417. The reversal of 21616384 is 48361612.

It is a happy number.

It is a super-3 number, since 3×21616384³ (a number of 23 digits) contains 333 as substring.

It is a plaindrome in base 11.

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, 1869 + ... + 6835.

It is an arithmetic number, because the mean of its divisors is an integer number (1269324).

Almost surely, 2^21616384 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 21616384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22847832).

21616384 is an abundant number, since it is smaller than the sum of its proper divisors (24079280).

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

21616384 is an equidigital number, since it uses as much as digits as its factorization.

21616384 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5000 (or 4986 counting only the distinct ones).

The product of its digits is 6912, while the sum is 31.

The square root of 21616384 is about 4649.3423190813. The cubic root of 21616384 is about 278.5657268424.

Adding to 21616384 its reverse (48361612), we get a palindrome (69977996).

The spelling of 21616384 in words is "twenty-one million, six hundred sixteen thousand, three hundred eighty-four".