21221732 has 48 divisors (see below), whose sum is σ = 45760512. Its totient is φ = 8411040.

The previous prime is 21221731. The next prime is 21221741. The reversal of 21221732 is 23712212.

It is not an unprimeable number, because it can be changed into a prime (21221731) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 19433 + ... + 20495.

It is an arithmetic number, because the mean of its divisors is an integer number (953344).

Almost surely, 2^21221732 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 21221732, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22880256).

21221732 is an abundant number, since it is smaller than the sum of its proper divisors (24538780).

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

21221732 is a wasteful number, since it uses less digits than its factorization.

21221732 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1128 (or 1126 counting only the distinct ones).

The product of its digits is 336, while the sum is 20.

The square root of 21221732 is about 4606.7051132018. The cubic root of 21221732 is about 276.8600386822.

Adding to 21221732 its reverse (23712212), we get a palindrome (44933944).

The spelling of 21221732 in words is "twenty-one million, two hundred twenty-one thousand, seven hundred thirty-two".