21604216 has 32 divisors (see below), whose sum is σ = 43146000. Its totient is φ = 10112256.

The previous prime is 21604213. The next prime is 21604223. The reversal of 21604216 is 61240612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21604213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12730 + ... + 14326.

Almost surely, 2^21604216 is an apocalyptic number.

It is an amenable number.

21604216 is a deficient number, since it is larger than the sum of its proper divisors (21541784).

21604216 is a wasteful number, since it uses less digits than its factorization.

21604216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1711 (or 1707 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 22.

The square root of 21604216 is about 4648.0335627015. The cubic root of 21604216 is about 278.5134482255.

Adding to 21604216 its reverse (61240612), we get a palindrome (82844828).

The spelling of 21604216 in words is "twenty-one million, six hundred four thousand, two hundred sixteen".