21001232 has 80 divisors (see below), whose sum is σ = 49996800. Its totient is φ = 8346240.

The previous prime is 21001187. The next prime is 21001247. The reversal of 21001232 is 23210012.

It is a happy number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 151019 + ... + 151157.

It is an arithmetic number, because the mean of its divisors is an integer number (624960).

Almost surely, 2^21001232 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 21001232, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (24998400).

21001232 is an abundant number, since it is smaller than the sum of its proper divisors (28995568).

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

21001232 is a wasteful number, since it uses less digits than its factorization.

21001232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 244 (or 238 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 21001232 is about 4582.7101152048. The cubic root of 21001232 is about 275.8978127621.

Adding to 21001232 its reverse (23210012), we get a palindrome (44211244).

The spelling of 21001232 in words is "twenty-one million, one thousand, two hundred thirty-two".