21771232 has 48 divisors (see below), whose sum is σ = 49617792. Its totient is φ = 9210240.

The previous prime is 21771221. The next prime is 21771247. The reversal of 21771232 is 23217712.

It is a junction number, because it is equal to n+sod(n) for n = 21771197 and 21771206.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 18007 + ... + 19177.

It is an arithmetic number, because the mean of its divisors is an integer number (1033704).

Almost surely, 2^21771232 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 21771232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24808896).

21771232 is an abundant number, since it is smaller than the sum of its proper divisors (27846560).

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

21771232 is a wasteful number, since it uses less digits than its factorization.

21771232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1271 (or 1263 counting only the distinct ones).

The product of its digits is 1176, while the sum is 25.

The square root of 21771232 is about 4665.9652806252. The cubic root of 21771232 is about 279.2293092167.

Adding to 21771232 its reverse (23217712), we get a palindrome (44988944).

The spelling of 21771232 in words is "twenty-one million, seven hundred seventy-one thousand, two hundred thirty-two".