21568416 has 48 divisors (see below), whose sum is σ = 56952000. Its totient is φ = 7147008.

The previous prime is 21568409. The next prime is 21568433. The reversal of 21568416 is 61486512.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18540 + ... + 19668.

It is an arithmetic number, because the mean of its divisors is an integer number (1186500).

Almost surely, 2^21568416 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 21568416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (28476000).

21568416 is an abundant number, since it is smaller than the sum of its proper divisors (35383584).

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

21568416 is a wasteful number, since it uses less digits than its factorization.

21568416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1341 (or 1333 counting only the distinct ones).

The product of its digits is 11520, while the sum is 33.

The square root of 21568416 is about 4644.1808750306. The cubic root of 21568416 is about 278.3595231152.

The spelling of 21568416 in words is "twenty-one million, five hundred sixty-eight thousand, four hundred sixteen".