21224532 has 48 divisors (see below), whose sum is σ = 58136960. Its totient is φ = 5899392.

The previous prime is 21224521. The next prime is 21224557. The reversal of 21224532 is 23542212.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a junction number, because it is equal to n+sod(n) for n = 21224499 and 21224508.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 307 + ... + 6522.

Almost surely, 2^21224532 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 21224532, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29068480).

21224532 is an abundant number, since it is smaller than the sum of its proper divisors (36912428).

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

21224532 is a wasteful number, since it uses less digits than its factorization.

21224532 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6880 (or 6878 counting only the distinct ones).

The product of its digits is 960, while the sum is 21.

The square root of 21224532 is about 4607.0090080225. The cubic root of 21224532 is about 276.8722144716.

Adding to 21224532 its reverse (23542212), we get a palindrome (44766744).

The spelling of 21224532 in words is "twenty-one million, two hundred twenty-four thousand, five hundred thirty-two".