21132416 has 32 divisors (see below), whose sum is σ = 43559100. Its totient is φ = 10200064.

The previous prime is 21132383. The next prime is 21132481. The reversal of 21132416 is 61423112.

It can be written as a sum of positive squares in 2 ways, for example, as 20286016 + 846400 = 4504^2 + 920^2 .

It is a tau number, because it is divible by the number of its divisors (32).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 866 + ... + 6558.

Almost surely, 2^21132416 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 21132416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21779550).

21132416 is an abundant number, since it is smaller than the sum of its proper divisors (22426684).

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

21132416 is an equidigital number, since it uses as much as digits as its factorization.

21132416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5736 (or 5724 counting only the distinct ones).

The product of its digits is 288, while the sum is 20.

The square root of 21132416 is about 4597.0007613660. Note that the first 3 decimals coincide. The cubic root of 21132416 is about 276.4710851392.

Adding to 21132416 its reverse (61423112), we get a palindrome (82555528).

The spelling of 21132416 in words is "twenty-one million, one hundred thirty-two thousand, four hundred sixteen".