21648616 has 64 divisors (see below), whose sum is σ = 48600000. Its totient is φ = 8924160.

The previous prime is 21648593. The next prime is 21648631. The reversal of 21648616 is 61684612.

It is a Harshad number since it is a multiple of its sum of digits (34).

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 15 ways as a sum of consecutive naturals, for example, 43135 + ... + 43633.

It is an arithmetic number, because the mean of its divisors is an integer number (759375).

Almost surely, 2^21648616 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 21648616, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24300000).

21648616 is an abundant number, since it is smaller than the sum of its proper divisors (26951384).

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

21648616 is a wasteful number, since it uses less digits than its factorization.

21648616 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 562 (or 558 counting only the distinct ones).

The product of its digits is 13824, while the sum is 34.

The square root of 21648616 is about 4652.8073246160. The cubic root of 21648616 is about 278.7041137175.

The spelling of 21648616 in words is "twenty-one million, six hundred forty-eight thousand, six hundred sixteen".