21753216 has 96 divisors (see below), whose sum is σ = 65398320. Its totient is φ = 6927360.

The previous prime is 21753209. The next prime is 21753257. The reversal of 21753216 is 61235712.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (96).

It is a self number, because there is not a number n which added to its sum of digits gives 21753216.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 26086 + ... + 26906.

Almost surely, 2^21753216 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 21753216, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32699160).

21753216 is an abundant number, since it is smaller than the sum of its proper divisors (43645104).

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

21753216 is a wasteful number, since it uses less digits than its factorization.

21753216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 864 (or 849 counting only the distinct ones).

The product of its digits is 2520, while the sum is 27.

The square root of 21753216 is about 4664.0343051912. The cubic root of 21753216 is about 279.1522659040.

Adding to 21753216 its reverse (61235712), we get a palindrome (82988928).

The spelling of 21753216 in words is "twenty-one million, seven hundred fifty-three thousand, two hundred sixteen".