21532416 has 108 divisors (see below), whose sum is σ = 61037928. Its totient is φ = 6735872.

The previous prime is 21532403. The next prime is 21532417. The reversal of 21532416 is 61423512.

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21532417) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 406246 + ... + 406298.

It is an arithmetic number, because the mean of its divisors is an integer number (565166).

Almost surely, 2^21532416 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 21532416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30518964).

21532416 is an abundant number, since it is smaller than the sum of its proper divisors (39505512).

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

21532416 is an equidigital number, since it uses as much as digits as its factorization.

21532416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 118 (or 81 counting only the distinct ones).

The product of its digits is 1440, while the sum is 24.

The square root of 21532416 is about 4640.3034383540. The cubic root of 21532416 is about 278.2045662352.

Adding to 21532416 its reverse (61423512), we get a palindrome (82955928).

The spelling of 21532416 in words is "twenty-one million, five hundred thirty-two thousand, four hundred sixteen".