21660352 has 42 divisors (see below), whose sum is σ = 50007012. Its totient is φ = 9281664.

The previous prime is 21660311. The next prime is 21660367. The reversal of 21660352 is 25306612.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 318 + ... + 6589.

Almost surely, 2^21660352 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 21660352, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25003506).

21660352 is an abundant number, since it is smaller than the sum of its proper divisors (28346660).

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

21660352 is an equidigital number, since it uses as much as digits as its factorization.

21660352 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6933 (or 6916 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 25.

The square root of 21660352 is about 4654.0683278181. The cubic root of 21660352 is about 278.7544676769.

Adding to 21660352 its reverse (25306612), we get a palindrome (46966964).

The spelling of 21660352 in words is "twenty-one million, six hundred sixty thousand, three hundred fifty-two".