21153232 has 40 divisors (see below), whose sum is σ = 43524000. Its totient is φ = 9931392.

The previous prime is 21153227. The next prime is 21153257. The reversal of 21153232 is 23235112.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 45063 + ... + 45529.

It is an arithmetic number, because the mean of its divisors is an integer number (1088100).

Almost surely, 2^21153232 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 21153232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21762000).

21153232 is an abundant number, since it is smaller than the sum of its proper divisors (22370768).

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

21153232 is a wasteful number, since it uses less digits than its factorization.

21153232 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 643 (or 637 counting only the distinct ones).

The product of its digits is 360, while the sum is 19.

The square root of 21153232 is about 4599.2642889923. The cubic root of 21153232 is about 276.5618325093.

Adding to 21153232 its reverse (23235112), we get a palindrome (44388344).

The spelling of 21153232 in words is "twenty-one million, one hundred fifty-three thousand, two hundred thirty-two".