21221632 has 36 divisors (see below), whose sum is σ = 44600080. Its totient is φ = 10050048.

The previous prime is 21221621. The next prime is 21221633. The reversal of 21221632 is 23612212.

It is a Harshad number since it is a multiple of its sum of digits (19).

It is not an unprimeable number, because it can be changed into a prime (21221633) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2683 + ... + 7045.

Almost surely, 2^21221632 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 21221632, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22300040).

21221632 is an abundant number, since it is smaller than the sum of its proper divisors (23378448).

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

21221632 is an equidigital number, since it uses as much as digits as its factorization.

21221632 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4398 (or 4384 counting only the distinct ones).

The product of its digits is 288, while the sum is 19.

The square root of 21221632 is about 4606.6942594446. The cubic root of 21221632 is about 276.8596038128.

Adding to 21221632 its reverse (23612212), we get a palindrome (44833844).

The spelling of 21221632 in words is "twenty-one million, two hundred twenty-one thousand, six hundred thirty-two".