21151232 has 40 divisors (see below), whose sum is σ = 42761400. Its totient is φ = 10450944.

The previous prime is 21151219. The next prime is 21151241. The reversal of 21151232 is 23215112.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 21151232.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 55619 + ... + 55997.

It is an arithmetic number, because the mean of its divisors is an integer number (1069035).

Almost surely, 2^21151232 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 21151232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21380700).

21151232 is an abundant number, since it is smaller than the sum of its proper divisors (21610168).

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

21151232 is an equidigital number, since it uses as much as digits as its factorization.

21151232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 506 (or 490 counting only the distinct ones).

The product of its digits is 120, while the sum is 17.

The square root of 21151232 is about 4599.0468577739. The cubic root of 21151232 is about 276.5531160934.

Adding to 21151232 its reverse (23215112), we get a palindrome (44366344).

The spelling of 21151232 in words is "twenty-one million, one hundred fifty-one thousand, two hundred thirty-two".